Objective  To survey the condom usage of migrant construction workers when involved in commercial sex in Pudong New Area, Shanghai and analyze the influencing factors based on social cognitive theory. Methods  The cluster random sampling method was adopted and questionnaire surveys were carried out among 1 850 migrant construction workers from 3 randomly chosen construction sites. Univariate and multivariate Logistic regression analyses were used to explore social cognitive factors influencing the condom usage during commercial sex, including the knowledge of AIDS, self-efficacy, skills, and strategies of condom usage, psychosocial problems, and condom availability. Results  Among 1 850 migrant construction workers who finished the survey, 459 (24.8%) of them admitted having involved in commercial sex, which was relevant to residential location, income, and sexual orientation. Among those who had involved in commercial sex, only 51 (11.1%) of them used condoms each time. The univariate analysis showed that social cognitive factors such as cognition related to AIDS prevention, self-efficiency, skills, and strategies of condom usage, and condom availability were relevant to persistent condom usage (P<0.05). Cognition related to AIDS prevention (ORm=1.51, 95%CI=1.29-1.76), self-efficiency of condom usage (ORm=1.29, 95%CI=1.07-1.55), and condom availability (ORm=1.79, 95%CI=1.19-2.70) that determined the condom usage during commercial sex were screened by the multivariate Logistic stepwise regression analysis. Conclusion  There is a high prevalence of commercial sex involvement and relatively low proportion of condom usage among migrant construction workers in Pudong New Area, Shanghai. Education on cognition related to AIDS prevention, self-efficiency of condom usage, and condom availability should be enhanced for this population in order to decrease the risk of sexual transmitted diseases and AIDS infections.