目的  了解上海市浦东新区外来建筑男工在商业性行为中安全套的使用情况，并基于社会认知理论分析其影响因素。方法  采用整群随机抽样方法，在上海市浦东新区随机抽取3个建筑工地，对1 850名外来建筑工人进行问卷调查。采用单因素和多因素Logistic回归分析调查对象在商业性行为中影响安全套使用的社会认知因素，包括艾滋病（AIDS）认知、安全套使用的自我效能和技巧策略、社会心理问题和安全套可及性。结果  在完成调查的1 850名外来建筑男工中，有459人（24.8%）承认发生过商业性行为，家乡地区、收入和性取向三者与之有关。在发生商业性行为的人中仅51人能每次都使用安全套，占11.1%。单因素分析发现，社会认知因素如AIDS预防相关认知、安全套使用自我效能、安全套使用技巧和策略以及安全套可及性与坚持使用安全套有关（P<0.05）。通过多元Logistic逐步回归筛选出AIDS预防相关认知(ORm=1.51,95%CI=1.29~1.76)、安全套使用自我效能(ORm=1.29, 95%CI=1.07~1.55)以及安全套可及性(ORm=1.79,95%CI=1.19~2.70)决定了商业性行为中安全套的使用。结论  上海市浦东新区外来建筑男工发生商业性行为比例较高且能坚持使用安全套的比例很低，应该通过加强该人群AIDS预防相关认知、安全套使用自我效能和安全套可及性的干预来降低性传播疾病和AIDS感染风险。

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.