Newly diagnosed HIV-positive men who have sex with men (NHMSM) are at high risk of mental health problems but may also develop post-traumatic growth (PTG). According to the Common Sense Model, illness perception (including both cognitive representation and emotional representation) affects coping and health-related outcomes. A cross-sectional survey was conducted to examine the associations between illness perception and PTG among 225 NHMSM in Chengdu, China. Linear regression analyses indicated that the constructs of emotional representation subscale (beta = -0.49) and five cognitive representation subscales (timeline, consequence, identity, attribution to god's punishment/will, and attribution to chance/luck) (beta = -0.13 to -0.37) were negative correlates of PTG, while four other constructs of cognitive representation (coherence, treatment control, personal control, and attribution to carelessness) were positive correlates (beta = 0.15 to 0.51). No moderating effects were observed. The associations between five cognitive representation subscales and PTG were fully-mediated via emotional representation. The results indicate that interventions promoting PTG among NHMSM are warranted and should alter illness perception, emotional representation in particular. Future studies should clarify relationships between cognitive representation and emotional representation, and extend similar research to other health-related outcomes and HIV-positive populations.