Social media trust is one of the important factors affecting the users' perceived privacy risk and self-disclosure. This article constructs a mediation model of network interpersonal trust in which social media trust in?uences perceived privacy risk and self -disclosure. With data collected from 501 social media users, this paper analyses the data using the Structural Equation Model. The empirical results show that: 1. perceived privacy risk is not related to the self-disclosure; 2. social media trust has a negative impact on perceived privacy risk of users, and network interpersonal trust plays a mediating role in their relationship; 3. social media trust positively in?uences the user's self-disclosure, and network interpersonal trust plays a mediating role in the relationship of them. Therefore, this study has a theoretical contribution to understanding the explanatory mechanism of social media trust on privacy risk perception and self-disclosure.