A Clinical Trial of an Quadrivalent Inactivated Influenza Vaccine in Healthy Children Aged 6 to 35 Months

Inclusion Criteria: * Healthy infants and young children aged 6-35 months, provide vaccination certificate and birth medical certificate. * The subject or legal guardian can provide with informed consent and sign the informed consent form. * The subjects or legal guardians are able to and willing to use a thermometer, a scale and fill in a diary card/contact card as required, and be able to comply with the requirements of the clinical trial protocol to complete clinical research. Exclusion Criteria: 1. st dose: * Axillary temperature\>37.0℃ * Participants aged 24-35 months, with abnormal blood routine, blood biochemical and urine routine indexes and judged by the researchers as having clinical significance. * Influenza within the past 3 months (confirmed clinically, serologically or microbiological). * Have previously received any influenza vaccine (registered or experimental) or planned to receive any influenza vaccine during the study. * Allergy to any component of the study vaccine, history of allergic reaction to eating eggs or using gentamicin sulfate. * History of severe allergies to any vaccines or drugs. * Preterm (delivered before 37 weeks of gestation), low birth weight (birth weight \<2500g) infants (only for volunteers aged 6 months to 12 months). * Dystocia, suffocation rescue, nervous system damage history. * Congenital malformations or developmental disorders affecting organ function, genetic defects, severe malnutrition, etc.. * Acute illness, severe chronic illness, or acute exacerbation of chronic illness on the day of vaccination. * History of vaccination with the live attenuated vaccine within 14 days prior to vaccination and other vaccination within 7 days. * Those receiving immune enhancement or inhibitor therapy within 3 months (continuous oral or infusion for more than 14 days). * Have congenital or acquired immunodeficiency, HIV infection, lymphoma, leukemia, or other autoimmune diseases. * History of asthma, unstable in the past two years requiring urgent treatment, hospitalization, intubation, oral or intravenous corticosteroids. * Receive blood or blood-related products within 3 months. * Have a medical history or family history of convulsion, epilepsy, encephalopathy and psychosis. * History of coagulation abnormalities (eg, coagulation factor deficiency, coagulation disorder) * Plan to relocate before the end of the study or to be away from home for an extended period of time during scheduled study visits * Participating in or planning to participate in other clinical trials in the near future * Abnormal laboratory test indicators, except for minor abnormalities that have no clinical significance as judged by the doctor. * The investigator judges any situation that is inappropriate to participate in this clinical trial 2. nd dose: * Severe allergic reaction after the first dose of the vaccine. * Serious adverse reactions causally related to the first dose of the vaccine. * After the first vaccination, newly discovered or newly occurred do not meet the first-dose inclusion criteria or meet the first-dose exclusion criteria will be determined by the investigator whether to continue participating in the study. * Other reasons for exclusion in the opinion of the investigator.