Abstract: Based on the China Education Panel Survery (CEPS) data, the impact of peer groups is analyzed on adolescent physical exercise behaviors in China through descripitive statistical analysis to build the least square linear (OLS) regression model, coeffcient clustering analysis and other methods.The results show that:① There is a very strong peer effect on adolescent physical exercise, which accounts for about 80% of the individual effects and greatly exceeds the effects from family, class, and school. ② Peer effect on adolescent physical exercise time differs significantly between boys and girls. For boys, peer effect is stronger than any other factors; while for girls, peer effect is weaker than that from individuals, class and schools. ③ Heterosexual friends, especially for boys, play a greater role in the promotion of physical exercise time; while for girls, the only child's physical exercise time significantly increases conpared with the non-only child' s. These factors should be fully taken into account in the planning of promoting adolescent physical exercise. In addition, the level of adolescent physical activity could be improved through the intervention of peer groups.