Abstract: ObjectiveTo analyse attitude to premarital sex behavior and its influncing factors among unmarried young people.MethodsBased on the data collected by face-to-face interview with 2 580 pairs who participated in required premarital physical examination,their attitude toward premarital sex behavior and the its influencing factors were analyzed.ResultsSubjects had an open attitude,71.27% of males and 60.69% of females thought unmarried youth mighthave sex behavior if they love each other or if they want to.Their attitude related to their demographic characteristics,family environ2 ment and lifestyle.Subjects who had the main living goal as being successful in work were less likely to approve the premarital sex behavior.Subjects knowing their peers had sex behavior or being sex experienced were more likely to approve premarital sex behavior.Male's attitude was consistent to their father's,while female's attitude was consistent to their mother's.Mother's discipline had effect on male's attitude,while father's discipline had effect on female's attitude.Females who had more love affair were more likely to approve the premarital sex behavior.Males who did not know induced abortion had negative effects on women's health were more likely to approve premarital sex behavior.ConclusionThe results indicated that much should be done in order to help young people to develop appropriate attitude,particularly to encourage them to have life aspiration.More attention should be given to subjects who worked in service providing company.Parents played a leading role in shaping their children's attitude.