Inclusion Criteria:  Aged 3 years and above (after enrolled, subjects will be allocated according to age). By asking for medical history and physical examination, the health condition judged by the investigators is well. Female subjects of childbearing age are not nursing or pregnant at the time of enrolment (negative urine pregnancy test) and have no family planning within the first 3 months after enrolment. Effective contraceptive measures have been taken within 2 weeks before inclusion. No vaccination history of COVID-19 vaccine before enrollment. Be able and willing to complete the whole prescribed study plan. With self-ability to understand the study procedures, the informed consent & voluntarily sign an informed consent form and be able to comply with the requirements of the protocol.  Exclusion Criteria:  Confirmed cases, suspected cases or asymptomatic infections of SAR-CoV-2 infection (check "China Disease Prevention and Control Information System"). Has a history of SARS, MERS infection (self-report, on-site inquiry). >14-year-old subjects axillary temperature ≥37.3℃, ≤14-year-old subjects axillary temperature ≥37.5℃. Previous severe allergic reactions to vaccination (such as acute allergic reactions, urticaria, dyspnea, angioneurotic edema or abdominal pain) or allergy to known ingredients of inactivated SARS-CoV-2 vaccine have occurred. With severe liver diseases, severe kidney diseases, uncontrollable hypertension (systolic blood pressure ≥160 mmHg, diastolic blood pressure ≥100 mmHg), diabetic complications, malignant tumors, various acute diseases, or acute attack period of chronic diseases. Has been diagnosed with congenital or acquired immune deficiency, HIV infection, lymphoma, leukemia or other autoimmune diseases. Has a history of convulsion, epilepsy, encephalopathy or mental illness or family history. With congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc. Has a history of coagulation dysfunction (e.g. Coagulation factor deficiency, coagulation disease). Received immunotherapy or inhibitor therapy within 3 months (continuous oral or infusion for more than 14 days). Received live attenuated vaccinewithin 1 month before this vaccination, other vaccines are inoculated within 14 days before this vaccination. Received blood products within 3 months before enrolment. Received other research drugs within 6 months before enrolment. Other circumstances judged by investigators are not suitable for this clinical trial.