Clinical Trial of Quadrivalent Influenza Virus Split Vaccine

Inclusion Criteria: * Healthy infants aged 6-35 months. * Volunteer legal guardian or client informed consent, voluntarily participate in and sign informed consent. * The volunteer legal guardian or client has the ability (non-illiterate) to understand the study procedures, to use a thermometer, scale, and fill in a diary card as required, and be able to complete the clinical study in compliance with the clinical trial protocol. Exclusion Criteria: * The underarm body temperature on the day of enrollment was \> 37.0℃. * Have been suffering from influenza within the previous 3 months (confirmed by either clinical, serological or microbiological methods). * Any previous influenza vaccination (registered or experimental) within 6 months or any planned influenza vaccination during the study period. * Allergic to any component of the vaccine, a history of allergic reactions to eggs or gentamicin sulfate. * A history of severe allergy to any vaccine or drug. * Preterm birth (delivered before 37 weeks of gestation), low birth weight baby (birth weight \< 2300g for girls, \<2500g for boys). * Dystocia, asphyxia rescue, nervous system damage history; * Congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc. * Acute illness, severe chronic illness or acute attack of chronic disease on the day of vaccination; * A history of live attenuated vaccination within 14 days prior to vaccination and a history of other vaccinations within 7 days prior to vaccination; * Patients who received immunoenhancement or inhibitor therapy within 3 months (continued oral or intravenous administration for more than 14 days); * Congenital or acquired immune deficiency, HIV infection, lymphoma, leukemia or other autoimmune diseases; * History of asthma, past two years of instability requiring emergency treatment, hospitalization, intubation, oral or intravenous administration of corticosteroids; * Have received blood or blood-related products; * A history of convulsion, epilepsy, encephalopathy, guillain-barre syndrome, a history of mental illness or a family history; * A history of abnormal coagulation function (such as coagulation factor deficiency, coagulation disease); * Planning to relocate before the end of the study or to leave for an extended -period during the scheduled study visit; * Participating in or planning to participate in other clinical trials in the near future; * The investigators determined that any conditions were inappropriate to participate in the clinical trial.