Abstract: 396 students from three different colleges and universities in Heilongjiang and Shandong were subjected to the Online Deviant Behavior Questionnaire survey, Security Questionnaire Survey and Basic Psychological Needs Scale by cluster sampling to explore the effect of their psychological needs upon their online deviant behaviors, and to provide theoretic guidance for heightening network surfing security. The results showed that: (1) College boys scored higher in online deviant behavior than girls, and freshmen scored far less than senior students in this regard; (2) Every dimension of security sense was nega- tively correlated with the online deviant behavior among college undergraduates; (3) Basic psychological needs played a full me- diating role between online deviant behavior and security sense of undergraduates, with the ratio of the mediating effect ac- counting for up to54% of the total effect. Basic psychological needs is an important internal reason for the security sense to re- duce online deviant behavior among college undergraduates.