Abstract: Objective To investigate levels of immunoglobulin G (IgG) antibody to polio, measles, rubella and Japanese encephalitis among children aged 1-9 years in Ganyu, Jiangsu province, and provide evidence for the research of immunization program. Methods A total of 39 363 blood samples were collected from healthy children aged 1-9 years who were selected through cluster sampling in Ganyu, and enzyme-linked immunosorbent assay (ELISA) was conducted to detect 4 specific IgGs to polio, measles, rubella and Japanese encephalitis respectively. Results Among the serum samples detected, the positive rates for polio, measles, rubella and Japanese encephalitis were 97.5%, 96.3%, 97.9% and 95.9%, respectively. The statistical analysis showed that there were no significant sex or age specific differences in positive rate. Conclusion The antibody titers to polio, measles, rubella and Japanese encephalitis were high among the children aged 1-9 years in Ganyu, which might form an immunization barrier to block the possible outbreak and spread of these diseases.