Commercial sex plays a critical role in rapidly increasing heterosexual transmission of HIV in China. Low-paid female sex workers (FSWs) are especially vulnerable to HIV/AIDS. Because of the illegality and stigma associated with sex work, FSWs may constantly live with fears in their daily life. Based on cross-sectional study of 794 low-paid FSWs in China we described their psychological fears related to commercial sex and examined the associations between fears and HIV-related behaviors. Fear of HIV infection was significantly associated with consistent use of condoms with clients. However, fear of breaching sex worker identity significantly prevented the FSWs from consistently using condoms with clients and taking HIV tests. Fear of being arrested by the police was positively associated with consistent use of condoms but negatively associated with accessing HIV prevention services. Our findings underlined the importance of examining the triadic interaction of behavioral, psychological and environmental factors in HIV prevention interventions among low-paid FSWs.