Inclusion Criteria:

Inclusion Criteria for SAD, MAD and SE：

- Subjects should fully understand the content, process and possible adverse reactions
of the study, and voluntarily sign the informed consent form;

- The age at the time of signing the informed consent is between 18 and 45 years old
(including the critical value)

- Subjects with negative COVID-19 nucleic acid detection in screening period;

- The body mass index (BMI=body weight [kg]/height2 [m2]) at screening is 19~27kg/m2
(including the critical value), and the weight of men is ≥ 50kg, and that of women
is ≥ 40kg;

- The blood pregnancy test of female subjects in the screening period and the baseline
period is negative;

- Female subjects must agree to take effective contraceptive measures from the date of
signing the informed consent form to 30 days after the last administration:

1. Those with fertility: from the date of signing the informed consent form to 30
days after the last administration, ① avoid pregnancy, ② if having sex with the
opposite sex, agree to continue to use one or more forms of effective
contraception (such as verified intrauterine devices, bilateral tubal ligation
or correct use of condoms, excluding any form of hormonal contraceptives). If
the male partner has undergone an effective sterilization operation, additional
effective contraception measures should be taken when the sperm is uncertain);

2. Non-fertility: ① Postmenopausal (spontaneous amenorrhea ≥ 12 months, or
spontaneous amenorrhea ≥ 6 months and FSH>40 IU/L, without other obvious
pathological or physiological reasons) before screening; Or ② documented
surgical sterilization (such as hysterectomy, bilateral salpingectomy or
bilateral oophorectomy, etc.);

- Male subjects (including their female partners) must agree to take effective
contraceptive measures from the date of signing the informed consent form to 30 days
after the last administration:

1. Those who are fertile must agree to use condoms correctly. If their female
partners are women of child-bearing age and have fertility (have not undergone
hysterectomy, bilateral salpingectomy or bilateral oophorectomy and have no
medical proven ovarian failure), their female partners must take effective
contraceptive measures (such as oral/injection/vaginal or implantable hormone
contraceptives, or other physical barrier, surgery and other female
contraceptive methods) within 30 days after the last administration;

2. Those who are infertile, such as those who have undergone effective
sterilization operations, take additional effective contraceptive measures when
they are not sure whether they have sperm);

- Male subjects agree to avoid donating sperm within 30 days from the initiation of
drug administration until the last administration.

Inclusion Criteria for Phase II dose exploration:

- Subjects should fully understand the content, process and possible adverse reactions
of the study, and voluntarily sign the informed consent form;

- The age at the time of signing the informed consent is ≥ 18 years old;

- In the first 2 days (48 hours) before randomization, COVID-19 nucleic acid detected
by RT-PCR is positive;

- During the screening period, the subject is assessed by the research doctor as a
patient with mild to moderate COVID-19 infection;

- During the screening period, the subject is assessed by the research doctor and show
symptoms/signs of COVID-19 infection for the first time within 2 days before
randomization;

- At least one of targeted COVID-19 symptoms exists within the first 24 hours of
randomization and meets the corresponding severity;

- Female subjects must agree to take the drug from the date of signing the informed
consent form to 30 days after the last administration; Effective contraceptive
measures:

Those with fertility: from the date of signing the informed consent form to 30 days after
the last administration, ① avoid pregnancy, ② if having sex with the opposite sex, agree
to continue to use one or more forms of effective contraception (such as verified
intrauterine devices, bilateral tubal ligation or correct use of condoms, excluding any
form of hormonal contraceptives). If the male partner has undergone an effective
sterilization operation, additional effective contraception measures should be taken when
the sperm is uncertain);

- Male subjects (including their female partners) agree to take effective
contraceptive measures from the date of signing the informed consent form to 30 days
after the last administration:

1. Those who are fertile must agree to use condoms correctly. If their female
partners are women of child-bearing age and have fertility (have not undergone
hysterectomy, bilateral salpingectomy or bilateral oophorectomy and have no
medical proven ovarian failure), their female partners must take effective
contraceptive measures (such as oral/injection/vaginal or implantable hormone
contraceptives, or other physical barrier, surgery and other female
contraceptive methods) within 30 days after the last administration

2. Those who are infertile, such as those who have undergone effective
sterilization, take additional effective contraceptive measures when they are
not sure whether they have sperm).

- The pregnancy test of female subjects in the screening period and the baseline
period is negative;

- Male subjects agree to avoid donating sperm within 30 days from the start of
administration until the last administration

Exclusion Criteria of SAD, MAD and SE:

- According to the judgment of the principal investigator, the participant is
accompanied with suspected COVID-19 related clinical symptoms/signs;

- During screening, those who are judged to be clinically significant by the principal
investigator through medical history inquiry, physical examination, vital signs,
blood oxygen saturation (SpO2), laboratory examination, 12-lead electrocardiogram
(ECG), abdominal ultrasound, chest X-ray examination, etc;

- Participants with clinically significant diseases (such as neuropsychiatric system,
cardiovascular system, urinary system, digestive system, respiratory system,
skeletal muscle system, endocrine and metabolic system, blood system, skin disease,
immune system, tumor, etc.) are evaluated by the researcher as not suitable for this
study;

- Previous major surgery, or according to the judgment of the principal investigator,
there is any physiological or disease or condition that may affect the absorption of
the study drug (such as gastrectomy, cholecystectomy, enterotomy, etc.);

- According to the judgment of the principal investigator, there is any physical or
psychological disease or condition that may increase the risk of the test, affect
the compliance of the subject with the other case, or affect the subject's
completion of the test;

- Within 2 weeks or 5 half-life (whichever is longer) before screening, and during the
whole study period, it is expected to take any medicine and health care products,
including prescription drugs, over-the-counter drugs and Chinese herbal medicine
(including oral contraceptives, external spermicide, drugs with systemic therapeutic
effects through percutaneous absorption and St. John's wort);

- Participants have participated in any clinical study or taken study drugs within 3
months before screening;

- Have a history of vaccination within 30 days before screening, or plan to have a
vaccination throughout the study period;

- Difficult in blood sample collection, unable to tolerate multiple venous blood
collection and any contraindication of blood sample collection;

- Large amount of blood loss or donation (more than 250mL) within 3 months before
screening;

- At screening, 12-lead ECG is abnormal and had clinical significance according to the
judgment of the researcher, such as the QT interval (QTcB) corrected by Bazett
(formula QT/RR0.5), the absolute value of QTcB in males is more than 450ms, and the
absolute value of QTcB in females is more than 470ms;

- When screening, endogenous creatinine clearance rate is less than 80mL/min,
according to Cockcroft-Gault formula: endogenous creatinine clearance rate
(mL/min)=(140 - age) × body weight (kg) 72 × serum creatinine concentration (mg/dL)
(female × 0.85);

- During the screening period and/or the baseline period, the blood pressure and pulse
are within the following range: systolic blood pressure <90 mmHg or ≥ 140 mmHg,
diastolic blood pressure <60 mmHg or ≥ 90 mmHg, pulse <55 bpm or >100 bpm;

- Have a history of drug dependence or drug abuse in the past, or have a positive
urine drug test during screening;

- Those who have a history of severe allergy to drugs, food and articles (including
allergy to latex, dust mites, pollen, etc.), or are known to be allergic to the test
drug ingredients;

- Within 2 weeks before screening, dieting or receiving dietary treatment for whatever
reason, or major changes in dietary habits;

- Have a history of alcoholism in the past (drinking more than 14 units of alcohol per
week on average), or drink more than 14 units of alcohol per time in the past two
weeks (1 unit=285mL of beer, 25mL of spirits, 125mL of wine), or cannot stop
drinking alcohol products during the test; Or positive alcohol breath test during
screening;

- Those who smoke more than 5 cigarettes per day on average in the three months before
screening, or who cannot stop using any tobacco products during the test;

- Within 2 weeks before screening, subjects ingested foods that may affect drug
metabolism, such as grapefruit juice;

- The average daily intake of coffee, tea, cola or other caffeinated drinks exceeds 6
cups (about 250mL per cup) within 3 months before screening;

- Those who have difficulty swallowing solid preparations such as tablets;

- Female subjects are in pregnancy or lactation at the time of screening;

- This study may not be completed due to other reasons or the researcher judges that
it is not suitable for participants.

Exclusion Criteria for Phase II dose exploration:

- The medical condition indicates that COVID-19 causes clinical signs of severe
systemic diseases, such as respiratory rate ≥ 30 times/minute, heart rate ≥ 125
times/minute, blood oxygen saturation (SpO2) ≤ 93% or PaO2/FiO2<300 mmHg within 24
hours before randomization (under indoor air conditions at rest), and it is urgent
or expected to require nasal high-flow oxygen therapy or non-invasive positive
pressure ventilation, invasive mechanical ventilation or ECMO.

- According to the judgment of the researcher, the medical condition suggests that
COVID-19 may develop into severe/critical status in the next 48 hours;

- Other than COVID-19, suspected or confirmed acute systemic infection (such as
combined influenza and bacterial infection) may interfere with the evaluation of the
research intervention response.

- Known history of active liver disease (excluding nonalcoholic fatty liver),
including acute or chronic active hepatitis B or C, primary biliary cirrhosis,
Child-Pugh grade B or C or acute liver failure.

- The patient is undergoing dialysis or is known to have moderate to severe renal
damage (that is, within 6 months before the screening visit, the CKD-EPI formula
based on serum creatinine eGFR < 45mL/min/1.73m2).

- They received anti-COVID-19 drugs (excluding NSAIDs) within 14 days before
randomization.

- Has received (within 30 days before randomization or within the half-life of 5
drugs, whichever is longer) or is expected to receive COVID-19 monoclonal antibody
or COVID-19 convalescence plasma treatment during the study period.

- Any anti-COVID-19 vaccine was inoculated within 3 months before randomization.

- Subjects who have to use potent CYP3A4/5 inhibitors and/or potent CYP3A4/5 inducers
from 7 days before screening to 7 days after the last administration for various
reasons.

- Subjects have major diseases (such as acute myocardial infarction, stroke, malignant
tumor, etc.) within 30 days before signing the informed consent form;

- Those who have difficulty swallowing solid preparations such as tablets;

- At the time of screening, the female subjects are in pregnancy or lactation.