Abstract: OBJECTIVE To analyze the epidemiological characteristics of influenza A (FluA) and influenza B (FluB) in a hospital of Nantong from 2024 to 2025 so as to provide bases for prevention and control of influenza and health care-associated infections (HAIs) management. METHODS The data regarding the nucleic acid tests for influenza viruses were collected from The Affiliate Hospital of Nantong University from Jan. 2024 to Dec. 2025. The seasonal prevalence, vulnerable populations, clinical characteristics and meteorological factors were observed. RESULTS From 2024 to 2025, the positive rate of FluA increased from 7.67% to 12.79%(χ²=12.703,P＜0.001), and the positive rate of FluB decreased from 3.39% to 0.13%(χ²=9.236,P=0.012),exhibiting a prevalence pattern dominated by FluA. Both FluA and FluB were highly prevalent in winter. There was significant difference in the positive rate of FluA among the seasons (all P＜0.05). In 2025, the prevalence rate of FluA was high among the infants, children, young and middle-aged populations, while it was low among the elderly population (χ²=132.337,P＜0.001). In 2024, the prevalence rate of FluB infection was 13.11% among the preschool children and 10.49% among the young population. FluA was more likely to be complicated with pneumonia, and the patients predominantly presented to the emergency internal medicine department and respiratory medicine department; fever and upper respiratory tract infections were the primary manifestations of the patients with FluB, and the patients mainly presented to fever clinic. The positive rates of FluA and FluB were negatively correlated with the temperature (all P＜0.001), intermediately negative correlation with precipitation (allP＜0.05), and positively correlated with PM_2.5 concentration (all P＜0.05). CONCLUSIONS FluA is predominant strain prevalent from 2024 to 2025, with the peak in winter; the infants, children, and young middle-aged are the susceptible populations and have more severe illness conditions. FluB is less prevalent and is more common among the children and young population. The low temperature, low precipitation and high concentration of PM_2.5 are the key driving factors for the flu epidemic.