Perceived stress among people living with HIV/AIDS (PLWH) was associated with severe mental health problems and risk behaviors. Discrimination toward PLWH in China is prevalent. Both perceived discrimination and social supports are determinants of the stress level among PLWH. Psychological support services for PLWH in China are scarce. It is unknown whether social support is a buffer between the perceived discrimination and perceived stress. With written consent, this study surveyed 258 PLWH recruited from multiple sources in two cities in China. Instruments were validated in previous or the present study, including the perceived stress scale for PLWH (PSSHIV), the perceived social support scale (PSSS), and the perceived discrimination scale for PLWH (PDSHIV). Pearson correlations and multiple regression models were fit. PDSHIV was associated with the Overall Scale and all subscales of PSSHIV, whilst lower socioeconomic status in general and lower scores of PSSS were associated with various subscales of PSSHIV. The interaction item (PSSS×PSDHIV) was nonsignificant in modeling PSSHIV, hence no significant moderating effect was detected. Whilst perceived discrimination is a major source of stress and social support can reduce stress among PLWH in China, improved social support cannot buffer the stressful consequences due to perceived discrimination. The results highlight the importance to reduce discrimination toward PLWH and the difficulty to alleviate its negative consequences. It is warranted to improve mental health among PLWH in China and it is still important to foster social support among PLWH as it has direct effects on perceived stress.