Abstract: Objective The present study was designed tO get an insight into the serum antibody levels after immunization with oral poliomyelitis vaccines in children aged from 1 to 7 years in Yuxi City．Methods 1972 children from 3 age groups of 1,4,7 years were selected and their poliomyelitis antibody levels were detected with ELISA．Results The positive rates of type I．Ⅱ and Ⅲ antibodies were 91,63％，97.87％ and 99.70％ with the geometric mean titer(GMT) being 1:187.99，1:503.54 and 1:838.03，respectively．The positive rates of antibody and GMT in 1-year，4-year and 7-year age groups were in a descending order in type Ⅲ，type Ⅱ and type I．Positive antibodies to all the 3 types of vaccines accounted for 89.96％ with no statistically significant difference between both sexes．The positive rate was relatively higher in mountain areas than in other areas．Conclusion The cold chain system for vaccines in the city of Yuxi iS in good condition，which contributes to guaranteeing the quality of OPV vaccination．There exist high levels of immune antibodies in the target population，forming an immune barrier against poliomyelitis．