Abstract: Objective: The Sixth National Census showed that the amount of migrant population in China reached 260 million in 2010，which had increased by about 120 million compared with "the fifth census". This epidemiological study was designed to explore the contraception knowledge level of migrant population in three cities, Beijing，Shanghai and Chengdu. Methods：This study was a multicenter cross-sectional survey. From Aug. to Dec. 2007，we chose 4 factories, 4 construction sites and 4 entertainment sites which were the gathered lots of migrant population in three cities. All the employees who met the inclusion criteria were included. Face-to-face questionnaire survey was done by those investigators trained uniformly. Database was established with Epidata 3.1，and data were inputted by two different persons and analyzed using SAS 9.1 package. Results：6 304 migrant population were actually investigated，including 2 001 from Shanghai，2 106 from Beijing and 2 197 from Chengdu. The knowledge levels of 9 common contraceptive methods, including their usage methods，principles，advantages and side effects, were scored. The average scores of 3 cities were all very low. The fitted multivariate linear regression model suggested that subjects from Beijing and Chengdu，male subjects，subjects unmarried and had no sexual behavior，subjects from construction sites，subjects who had lower capita income, and subjects who were agricultural residence registration, had lower scores. As for answering whether the six contraception could prevent HIV transmission，75.08% of subjects provided correct answer in the item of male condom，while only 40% subjects provided correct answer in the items of other 5 contraception methods. Conclusions：The knowledge levels of the usage, principles, advantages and side effects，and prevention against HIV transmission of common contraceptive methods, are still poor in migrant population. Subjects who are male，unmarried，haven′t sexual behavior, or are in bad economic status, are the key population of reproductive health services.

Key words: Population characteristics, Contraception, Knowledge, Epidemiologic factors