In the current information age, SNSs (Social Network Sites) have been popular among young adolescents, and have also become a main manner to maintain social relationships. Against this background, based on relevant evidence, the present study aimed to examine the association between positive self-disclosure on SNSs and adolescents' friendship quality, as well as the underlying mechanism-the potential mediating role of perceived positive feedback and the moderating role of social anxiety. A sample of 1713 adolescents aged 11 to 19 was recruited to participate in this study, to complete a set of scales. Results indicated that positive self-disclosure on SNSs was positively associated with adolescents' friendship quality, and positive feedback significantly mediated the association between self-disclosure positivity and friendship quality. This mediating effect, moderated by social anxiety, could significantly moderate the mediating effect of positive feedback; specifically, compared with higher social anxiety adolescents, the association between positive self-disclosure and positive feedback was stronger among individuals with lower social anxiety. These findings may expand previous studies, with several theoretical and practical implications.