Social networking site (SNS) has become one of the most influential and popular social applications in the information age because of its openness, archiving and interactivity, and the impact of SNS use has also become a focus of relevant research scholars. Teenagers are the most active users in SNS, so it has important influence on the establishment of interpersonal relationship, self-concept development and psychological social adaptation for teenagers. In recent years, the SNS as a potential risk factor for depression in adolescents has been taken seriously by researchers at home and abroad, but findings remain inconsistent: increase the risk of depression VS alleviate the symptoms of depression. There are studies that suggest that different types of social networking sites, such as active use and passive use, may be the leading cause of inconsistencies in previous studies, and scholars should explore the specific SNS use, such as passive SNS use “how to influence” individual psychology. Therefore, this study intends to explore the influence of passive SNS use on depression and its mechanism. Rumination and core self-evaluation are introduced as two variables to study the relationship between passive SNS use and depression as well as the possible mechanism underlying the relationship between passive SNS use and adolescents’ depression, and this study focused on the chain mediating role of both rumination and core self-evaluation between passive social network site use and adolescents' depression. A survey research method was adopted in which the Passive Social Network Site Use Scale, the short form of Ruminative Responses Scale, the Core Self-Evaluations Scale as well as the Center for Epidemiological Studies Depression Scale were administered to 673 middle school students. Data was collected and analyzed with SPSS 17.0, and the bias-corrected percentile Bootstrap method was used to analyze the chain mediating role of both rumination and core self-evaluation between passive social network site use and adolescents' depression. The results indicated: (1) The relationships between each pair of passive social network site use, and rumination as well as depression, were significantly positive. However, passive social network site use, rumination as well as depression were all negatively correlated with core self-evaluation. Passive social network site use not only had direct effect on depression, but also could significantly predict rumination and core self-evaluation; rumination could significantly predict core self-evaluation; both rumination and core self-evaluation could significantly predict depression. (2) Passive social network site use not only had direct effect on depression, but also could affect adolescents’ depression through three indirect paths: through the mediating role of rumination; through the mediating role of core self-evaluation; through the chain mediating role of both rumination and core self-evaluation. The present study highlights the chain mediating role of both rumination and core self-evaluation in the effect of passive SNS use on adolescents’ depression. It may contribute to our better understanding of how passive social network site use impacts adolescents’ depression from the Rumination Responses Theory and Vulnerability Model.