Objective:To investigate the appropriate age for booster doses of hepatitis B vaccine in children aged 0-14.Methods:Retrospective study.A total of 3 118 children aged 0-14 years who underwent quantitative serological marker testing for hepatitis B virus at the Affiliated Hospital of Hangzhou Normal University from January 2015 to October 2021 were recruited in this analysis.There were 1 702 males and 1 416 females, with a male to female ratio of 1.20∶1.00.Children were divided into 15 groups according to their age, and the classifying interval was 1 year.The hepatitis B virus surface antibody (Anti-HBs) titer was quantified by chemiluminescent microparticle immunoassay.The Anti-HBs positivity rates and hepatitis B immune response among groups of different sexes and age were compared by the chi- square test and rank- sum test, respectively. Results:A total of 3 118 children were investigated.The titer and effective response rate of Anti-HBs decreased gradually with age.The difference in the titer and effective response rate of Anti-HBs was statistically significant among groups of different age (all P<0.01), but not significant between males and females (all P>0.05). The median titer of Anti-HBs in children aged above 3 years was 58.49 IU/L(0-1 001.00 IU/L). About 59.1% (1 477/2 497 cases) of children aged 3 years and above had no immune response or low immune response (i.e., the titer of Anti-HBs was below 100 IU/L). Conclusions:The immune protective effect of the hepatitis B vaccine decreases year by year in children who have received the standardized vaccine, and the vaccine has poor protective effect on most children aged 3 years and above.Therefore, booster dose vaccination for preventing hepatitis B is necessary for children aged 3 and above.