Abstract: Positive interpersonal relationships play a crucial role in promoting the growth and success of college students. Active social networking sites, represented by WeChat, have become important arenas for college students' social interactions and exert significant influences on their interpersonal relationship satisfaction. However, the underlying mechanisms remain to be further clarified. To investigate the mechanisms through which active social networking site use, perceived social support, and empathy affect college students' offline interpersonal relationship satisfaction, this study adopted a questionnaire survey method. A sample of 688 college students was surveyed. The study examined the relationship between active social networking site use and offline interpersonal relationship satisfaction, the mediating role of perceived social support between these two variables, and the moderating role of empathy in the path from perceived social support to offline interpersonal relationship satisfaction. The results showed that active social networking site use positively and significantly predicted college students' offline interpersonal relationship satisfaction. Perceived social support partially mediated the relationship between active social networking site use and offline interpersonal relationship satisfaction. Empathy significantly and negatively moderated the association between perceived social support and offline interpersonal relationship satisfaction. These findings are of great significance for improving college students' mental health and enhancing their offline social competence.