This study investigates socio-demographic, behavioral, psychological, and structural factors associated with self-reported HIV/STD testing and willingness to test among 1,938 Chinese migrants. Overall, 6% and 14% of participants had ever been tested for HIV and STD, respectively. The results of multivariate analyses indicate that working at entertainment sectors, engaging in commercial sex, and utilization of health care were positively associated with both HIV and STD testing. Younger age, selling blood, perceived peer sexual risk involvement, and satisfaction with life were associated with HIV testing only. Female gender, early sexual debut, multiple sexual partners, and perceived vulnerability to HIV/STD were associated with STD testing only. Male gender, having premarital sex, perceived higher severity of and vulnerability to HIV/STD, and utilization of health care were associated with willingness to be tested for both HIV and STD. Interventions designed to raise the perception of vulnerability to HIV/STD and to improve access to and utilization of health care may be effective in encouraging more HIV testing in this vulnerable population.