Abstract: Objective To understand the infection status of hepatitis B virus (HBV) in pre-school aged children in Changping, Beijing, evaluate the vaccination effect and herd immunity, and provide evidence for the development of prevention and control strategies. Methods Totally 2128 children aged 0-6 years were selected in local population in Changping by multistage random cluster sampling, and blood samples were taken from them to detect HBsAg, anti-HBs and anti-HBc with ELISA. Comparison was made on the infection rates between the children whose mothers had been infected with HBV or not. Results The positive rates of HBsAg, anti-HBs and anti-HBc were 0.05%, 63.27% and 1.08% respectively and the total HBV infection rate was 1.08%. The positive rate of anti-HBs was 64.84% (924/1425) in urban area and 62.85% (442/703) in rural area, the HBV infection rate was 0.77% (11/1425) in urban area and 1.56% (11/703) in rural area. The positive rate of anti-HBs was 64.68% (718/1110) in boys and 63.65% (648/1018) in girls, the HBV infection rate was 0.81% (9/1110) in boys and 1.28% (13/1018) in girls. Conclusion Both the HBsAg positive rate and HBV infection rate in children remained to be low in Changping, indicating the effectiveness of hepatitis B vaccination since its inclusion in immunization programme.