This study aimed to examine the relationship between physical activity and cancer patients’ survival beliefs and constructed a mediation model involving the mediating effects of interpersonal competence and quality of life. We conducted 252 questionnaire surveys on multiple chat groups for cancer patients using the WeChat software, and assessed physical activity, survival beliefs, interpersonal competence, and quality of life using standard scales. Data were analyzed using SPSS and AMOS. There were positive correlations between physical activity and quality of life (β= 0.393,p< 0.001), physical activity and interpersonal competence (β= 0.385,p< 0.001), interpersonal competence and quality of life (β= 0.455,p< 0.001), and quality of life and survival beliefs (β= 0.478,p< 0.001). In addition, a significant mediating effect between physical activity and survival beliefs was observed between interpersonal competence and quality of life (standardized indirect effect = 0.384,p< 0.001). The study revealed that effective physical activity led to higher interpersonal competence, more excellent quality of life, and improved survival beliefs in cancer patients, and that the association of physical activity with improved survival beliefs was fully mediated through interpersonal competence and quality of life. The findings suggest that the relevant government should increase policy support and publicity to improve cancer patients’ participation in physical activity.