Abstract： Objective To understand the epidemiological characteristics of influenza and the monitoring of dominant strains in Nantong city from 2021 to 2022,and provide scientific basis for influenza prevention and control.Methods The information and pathogenic detection results of influenza-like illness(ILI)reported by the influenza surveillance sentinel hospitals in Nantong city from 2021 to 2022 were collected.The specimens of throat swab were collected from ILI cases for the detection of nucleic acids of influenza virus with real-time fluorescent quantitative PCR.All data was analyzed with descriptive epidemiological methods.Results The total number of the cases from outpatient and emergency department was 836 164 cases,with 78 965 cases of ILI,and 9.44％ of ILI％ in the two sentinel hospitals.The ILI％ was 6.47％ in 2021 and 13.38％ in 2022.There were 4 170 throat swabs collected,and 416 swabs were positive of influenza virus nucleic acid,accounting for 9.98％.The positive rate was 6.12％in 2021 and 13.85％ in 2022,with statistical difference(x2=69.213,P＜0.05).The difference of positive rates in different age groups was statistically significant(x2=298.580,P＜0.05).There was no statistical difference(x2=0.883,P＞0.05)in the positive rates of different genders.The epidemic of influenza showed double-peaks distribution in winter and spring,and summer.The epidemic strain was type B(Victoria)in 2021 and type A(H1N1,H3N2)in 2022.The influenza outbreaks were mainly occurred in primary and secondary schools,accounting for 91.78％.Conclusions The predominant strains of influenza virus are different in Nantong city from 2021 to 2022,with high positive rate and proportion.Influenza is still one of the key infectious diseases that needs to be prevented and controlled.