Abstract: Objective To determine the prevalence of hepatitis B surface antigens (HBsAg) and hepatitis B surface antibodies (anti-HBs) in 1-12 years-old children in Mianyang city, Sichuan Province. Methods Children born after the implementation of Hepatitis B immunization policy were selected using a stratified random cluster sampling strategy from January to December 2015. A total of 72 623 eligible children participated in the study, which included a questionnaire survey and blood tests (0.3 mL vein blood) for HBsAg and anti-HBs with ELISA method. Repeated tests were performed on the blood samples with a HBsAg positive result. Results About 0.24% of the children were HBsAg positive; 64.50% were anti-HBs positive; 35.26% were both HBsAg and anti-HBs negative. The standardized rates based on the 2010 population census were: 0.24% HBsAg positive, 64.05% anti-HBs positive, and 35.71% both HBsAg and anti-HBs negative. HBsAg positive rates increased with age, ranging from 0% to 0.65% (P<0.001). Rural children had a higher HBsAg positive rate (0.32%) than their urban counterparts (0.16%, P<0.001). Those with a family history of Hepatitis B had a higher HBsAg positive rate (1.53%) than those without a family history (0.22%, P<0.001). Anti-HBs positive rates decreased withage, ranging from 47.85% to 71.43% (P<0.001). Rural children had a lower anti-HBs positive rate (62.06%)than their urban counterparts (66.81%, P<0.001). The prevalence of both HBsAg and anti-HBs negative cases increased with age, ranging from 28.57% to 51.98% (P<0.001). Rural children had a higher rate of both HBsAg and anti-HBs negative (37.62%) than their urban counterparts (33.03%, P<0.001). About 35.37% of the children who had negative HBsAg and anti-HBs had not received Hepatitis B immunization. Conclusions Hepatitis B vaccinations are highly effective in Mianyang. However, there are disparities in anti-HBs positive rates between the children with different characteristics. A certain proportion of children are still susceptible to hepatitis B infection. It is necessary to attach importance to neonatal hepatitis B vaccination, surveillance on anti-HBs, and strengthened immunization for the children who are lack of antibody protection.