Objective: Study 1 of the present research will explore the relationship between cognitive emotion regulation and social anxiety. Study 2 will exam whether cognitive behavioral group therapy can relieve social anxiety and negative cognitive emotion regulation among college students. Methods: We conducted a survey among 528 college students by using Cognitive Emotion Regulation Questionnaire and Interaction Anxiousness Scale. Then we selected 15 students who got higher scores to participate in the cognitive behavioral group therapy which last for 8 weeks and examined pre-to post-CBGT changes in cognitive emotion regulation and social anxiety. Results: (1) Study 1: There are positive correlations between negative cognitive emotion regulation and social anxiety. On the contrary, there are negative correlations between positive reappraisal and social anxiety. Catastrophizing, self-blaming, positive reappraisal and rumination are effective predictors of social anxiety. (2) Study 2: Cognitive behavioral group therapy can evidently reduce social anxiety, catastrophizing, self-blaming and rumination, but had no significant effect on positive reappraisal. Conclusions: (1) Negative cognitive emotion regulations (self-blaming, rumination, catastrophizing, and blaming-others) have positive correlations with social anxiety. Contrarily there are negative correlations between positive reappraisal and social anxiety. (2) Catastrophizing, self-blaming, positive reappraisal and rumination are effective predictors of social anxiety. (3) Cognitive behavioral group therapy can evidently reduce social anxiety. (4) Cognitive behavioral group therapy can alleviate the use of negative regulations such as catastrophizing, self-blaming and rumination.