Abstract: Objective To understand the circum stance of sexually transmitted diseases(STD)related knowledge and non-marriage sexual behavior among urban peasant workers,and analyze the influencing factors of non marriage sexual be havior.Methods A total of 700 peasant workers of the local mainstream industry(shoem aking,electronic and machinery industry)were investigated with anonymous questionnaire.The influencing factors of non marriage sexual behavior were analyzed by non conditional logistic regression analysis.Results Among 635 peasant workers,the recognition of AIDS was the best(46.85%)and that of gonorrhea was the poorest.42.2% of the subjects was with the knowledge score of zero 0 and only 2.83% with complete knowledge of AIDS.There were 249 peasant workers(39.21%)had non marriage sexual behavior and only 113 persons(45.38%)using condomeach time.The influencing factors of non marriage sexual behavior was prmiary school education(OR=4.28),male(OR=2.14)and over 35 years old(OR=5).AIDS knowledge(OR=2.19)was the factors affecting the condom using in non marriage sexual behavior.Conclusion Some peasant workers in Zhaoqing city are lack of STD related knowledge and the non marriage sexual behavior is common among them.The health education of STD related knowledge and intervention in non marriage sexual behavior should be carried out in the population with low education,male and over 35 years old.