Objective To explore whether condom use is influenced by power relation in commercial sex behaviors. Methods Variables were designed to measure the power relation in commercial sex behaviors based on the theory of gender and power relation and data were collected from male sexually transmitted diseases (STD) patients and female commercial sex workers (FSWs) working at recreation centers or being detained in a women education center to identify the relationship between condom use and power relation in male and female respondents using bivariate and multiple regression analysis. Results A significant relationship was identified between power relation and female condom use, the higher the score of power relations, the higher frequency the condom use, but no similar result was found in males. Females got a higher score of power relation than males. Conclusions Power relation is one of the factors that influence condom use, which should be considered when relevant theories are used to study the rate of condom use. It is worthwhile exploring the relationship between safe sex and power relation in spouses and regular sex partners when interventions are adopted to prevent HIV/AIDS spreading from high risk groups to the general population.