In order to explore the relationship between college students’ use of social networking sites,self-concept clarity and social anxiety, 305 college students with experience in using social networkingsites were investigated with the Active Passive Social Networking Site Use Scale, the Self Concept ClarityScale, and the Social Anxiety Scale. The results showed that: (1) Social anxiety of college students wassignificantly different in gender, but not in grade and independence. (2) There is a positive correlationbetween college students’ self-concept clarity and social anxiety, a negative correlation between collegestudents’ passive social networking sites and self-concept clarity, and a negative correlation betweencollege students’ passive social networking sites and social anxiety. (3) College students’ use of socialnetworking sites has a positive predictive effect on social anxiety.