【Objective】 To investigate the anti-HBs(hepatitis B virus surface antibody) level of children entering nurseries or kindergartens in Ningbo city after basic hepatitis B vaccination. 【Methods】 466 children in Ningbo city entering nurseries or kindergartens who had finished 3 times basic hepatitis B vaccination were enrolled the study by using the method of random sampling and their HBsAg(hepatitis B virus surface antigen) and anti-HBs levels were detected. 【Results】 The average rate of HBsAg carring and high anti-HBs level were 0 and 30.69%;The incidence of high anti-HBs level in groups aged 1.5~2,3,above 4 were 35.42%,29.24% and 15.79%;The incidence of high anti-HBs level in groups vaccination during the first month and surpass one month after birth were 27.25% and 55.56%. 【Conclusions】 The anti-HBs level of children entering nurseries or kindergartens is low,and it is dropped with the increase of ages.A supplementary immunization was proposed to the low or no anti-HBs level healthy child.