Patient Inclusion Criteria

- 1. Aged between 18 and 75 years, extremes included, male or female - 2. Laboratory (RT-PCR) and clinical symptoms confirmed case of 2019-nCoV pneumonia, according to the official guideline "Pneumonia Diagnosis and Treatment Scheme for Novel Coronavirus Infection (Trial Version 5)" - 3. Hospitalised with a new onset respiratory illness (≤7 days since illness onset) - 4. No family planning within six months, and agree to take effective contraceptive measures throughout the study and for at least 30 days after the final study drug dose - 5. Must agree not to enroll in another study of an investigational agent prior to completion of Day 30 of study - 6. Informed Consent Form (ICF) signed voluntarily

Patient Exclusion Criteria

- 1. Severe 2019-nCoV pneumonia met one of the following criteria: respiratory distress, RR ≥ 30 times / min, or SaO2 / SpO2 ≤ 93% in resting state, or arterial partial pressure of oxygen (PaO2) /concentration of oxygen (FiO2) ≤ 300mmHg (1mmHg = 0.133kpa) - 2. Critical severe 2019-nCoV pneumonia met one of the following criteria: respiratory failure and mechanical ventilation required, or shock, or combined with other organ failure required ICU monitoring treatment - 3. Severe liver disease (e.g. Child Pugh score ≥ C, AST > 5 times upper limit) - 4. Known allergic reaction to any of components of ASC09 / ritonavir compound tablets - 5. Patients with definite contraindications in the label of ritonavir - 6. Positive serum pregnancy test result for women with childbearing potential at screening - 7. Using HIV protease inhibitor drugs - 8. Not suitable for the study, in the opinion of the Investigator (e.g. patient may be transferred to another hospital during the study period, patient with multiple basic diseases, etc.)