Social media refers to highly interactive platforms where people employ mobile and web-based technologies to share, co-create, discuss, and modify user-generated content （Kietzmann, Hermkens, McCarthy, & Silvestre, 2011）. With the development of the Internet, more and more people choose to use the Internet to interact with their offline friends as well as strangers they met online. Therefore, Internet interaction has been popular all over the world and has brought great convenience to people’s studies, work, entertainment and so on. Among all the users, the proportion of college students that constantly engaged in Internet interaction is quite high in China （China Internet Network Information Center, 2017）. Researchers have revealed that Internet interaction has both positive and negative effects on college students’ physical and mental health development. However, the specific outcome might depend on whether and how Internet interaction meet users’ needs （Suler, 1999）. The extant researches indicated that people prefer to use Internet interaction in order to satisfy their psychological needs that real life interaction could not achieve （Cai, Cui, & Li, 2007; Wan, Liu, & Fang, 2012）. Hence, psychological needs have quite important influence on college students’ Internet interaction. Yet little is known about the mediating and moderating mechanisms underlying this relation. This study aimed at filling this gap. The mediation mechanism can tell us how the independent variable （psychological needs） has effect on the dependent variable （Internet interaction）, and the moderation mechanism can inform us how the relationship between the independent variable （psychological needs） and the dependent variable （Internet interaction） is influenced by the moderator （self-regulation）. This study proposed a moderated mediation model to examine whether the relationship between psychological needs and Internet interaction was mediated by the cognitive assessment and was moderated by the self-regulation. Psychological Needs Scale for College Students, Internet Decisional Balance Questionnaire, Self-Regulation Scale and Internet Interaction Questionnaire for University Students were administrated to 503 college students （M = 21.66 years, SD = 1.67）. Data were collected and analyzed with SPSS 20.0, and the bias-corrected percentile Bootstrap method was used to analyze the mediating role of cognitive assessment and the moderating role of self-regulation. The results indicated that: （1） The relationships between each path of psychological needs, the pros of Internet, the cons of Internet, self-regulation and Internet interaction, were significantly positively related. （2） College students’ psychological needs positively predicted their Internet interaction, and this relationship was partly mediated by the pros of Internet and the cons of Internet. （3） The relationship between psychological needs and Internet interaction was moderated by the self-regulation. For college students with high self-regulation, psychological needs positively predicted their Internet interaction. However, for college students with low self-regulation, psychological needs could not predict Internet interaction. These findings highlighted the complex nature of association between college students’ psychological needs and their Internet interaction, providing constructive advises for college students to develop a healthy habit of Internet interaction.