Social media has deeply changed the interpersonal communication. With the popularity of mobile Internet, appearance of mobile social media, the communication between people is becoming more different. More and more young people started to use mobile social media to communicate with their classmates and friends. But few studies have focused on the adolescents’ behaviors on using mobile social media activities and whether the use of mobile social media will affect the quality of their friendship, and how it will be affected. Studies have found that there is a close connection between the use of social media and adolescents’ friendship quality. In addition to all the features of traditional social media, mobile social medial also has its own unique characteristics. It is convenient and can be used anytime and anywhere. How will the use of mobile social media affect adolescent’s friendship quality, and what is the relationship between mobile social media and adolescent’s friendship quality? Further analysis and verification are still needed. Mobile social media refers to the traditional social media were used on mobile devices(e.g., smartphones, pad.), and the software that had social features specifically developed for mobile devices, such as SMS, social networking sites, micro-blog, mobile QQ, and wechat. The current study examined the effect of mobile social media on friendship quality of Chinese adolescents, and how such an effect might be mediated by online self-disclosure and online social support. The participants were recruited from four middle schools in Shanxi province and Anhui province. All participants were tested in groups in classroom settings. We recruited 600 students with average age of 14.42. They were asked to complete Adolescents’ Mobile Social Media Usage Scale, Online Self-disclosure Scale, Online Social Support Scale and the Scale of Friendship Quality. There are 560 students completed the survey (i.e., response rate was 93.3%), 473 students using mobile social media contacted with their classmates or friends, and 87 students never used mobile social media. Thus the data analysis does not include this part of samples that never used mobile social media. Results provide strong support for the hypothesis that Mobile social media was positively correlated with adolescents’ friendship quality, online self-disclosure, and online social support (p<0.01). Structural equation modeling showed that there are two ways that mobile social media use predicted the adolescents’ friendship quality: The first is that mobile social media use can affect adolescents’ online social support, and then affect the friendship quality via online social support. And the second is that mobile social media use can affect the adolescents’ online self-disclosure, and then online self-disclosure will affect the friendship quality via online social support. Online self-disclosure and online social support play a serial mediation role between the mobile social media use and friendship quality. The present study examined how the social media use on the mobile devices affect the friendship quality of adolescents in China, it answered the question that how the mobile social media use affect the adolescents’ interpersonal relationships. The present study resolve the core questions of how mobile technology use affect physical, cognitive, social, emotional, and moral development of children and adolescents in the world.