Objective：To explore the changing regularity of the incidence trend of four types of hepatitis（hepatitis A，hepatitis B， hepatitis C and hepatitis E）in China before and after the coronavirus disease-2019（COVID-19）pandemic between 2019 and 2023， and provide a reference for the prevention and treatment of hepatitis after the epidemic. Methods：Based on the descriptive statistics and seasonal decomposition of the four hepatitis time series between 2012 and 2023 in China，the monthly cases before and after the COVID-19 pandemic in 2019 and 2023 were compared and analyzed，as well as the long-term trend，seasonal factors and the dynamic change of variance contribution rate of the time series. Results：During the COVID-19 epidemic between 2020 and 2022，the average monthly cases of four types of hepatitis were lower than that in 2019 before the epidemic，each type of hepatitis had reached its lowest historical value since 2012，and the monthly cases of 2023 after the epidemic appeared an upward trend. The decomposition of time series showed that the seasonal factors of hepatitis A，B，C，and E in 2012- 2019 and 2012- 2023 were highly correlated，with correlation coefficients of 0.964，0.964，0.947，and 0.977，respectively（all P < 0.001）. The variance of the time series of the four types of hepatitis of 2012-2019，2012-2020，2012-2021，2012-2022，2012-2023 showed an upward trend，the long-term trend variance contribution rates showed an upward trend，with correlation coefficients of 0.979，0.981，0.890，and 0.938 with variance，respectively （all P < 0.05），but the seasonal factor variance contribution rates showed a downward trend，with correlation coefficients of -0.978， -0.986，-0.954，and -0.936 with variance，respectively（all P < 0.05）. Conclusion：The decomposition of the time series is helpful to study the regularity of the long -term trend changes and periodic fluctuation of hepatitis. The long -term trend is obvious for the time series diagram of hepatitis A or B，and the periodic fluctuation is obvious for the time series diagram of hepatitis C or E. The epidemic prevention and control have reduced the monthly cases of four types of hepatitis，which has a significant impact on the long-term trend of monthly cases but has not changed the cyclical characteristics of the low and peak periods of incidence. Faced with the challenge of an increase in the cases of hepatitis after the epidemic，it is necessary to strengthen the monitoring of hepatitis，explore the regularity of hepatitis incidence，and do a good job in prevention，control and treatment of hepatitis.