Objective: To study the specific correlation between physical activity intensities and body compositions of adolescents and to provide guidance for the improvement of various body compositions of Chinese adolescents. Methods: From September to December 2019, body composition measurement based on bioelectrical impedance analyzer and the physical activity measurement based on accelerometers were performed among 971 adolescents from 8 high schools, such as Tsinghua Middle School in Beijing, by random number coding sampling. Statistical analysis was conducted by using independent sample t test, Pearson correlation coefficient method and multiple linear regression method. Results: Sedentary behavior(SB) of the junior and senior high school boys was significantly lower than that of girls, while the VPA(vigorous physical activity) and moderate vigorous physical activity(MVPA) were significantly higher than those of boys ( t =-1.98, -8.09; 5.20, 4.52; 3.53, 4.03, P <0.05). light physical activity(LPA) and moderate physical activity(MPA) of boys were significantly higher than those of girls in the senior high schools ( t =3.67, 5.63, P <0.01). Lean mass(LM) of the junior school boys was correlated to their MVPA( β =0.302), bone mineral content(BMC) was quantitively related to SB( β =-0.001), MVPA( β =0.002), and fat mass(FM) was related to SB( β =0.050), and MVPA( β =-0.323) ( P <0.05). LM of junior school girls was quantitively correlated to LPA ( β =0.080) and MVPA( β =0.613). And there was also correlation among BMC ,SB( β =-0.004) and MVPA( β =0.008) between FM and MVPA( β =-0.237) ( P <0.05) . There was a correlation between total body LM and MVPA ( β =0.393), total body BMC and SB ( β =-0.001), MVPA ( β =0.002), and total body FM and MVPA ( β =-0.393) in senior high school boys( P <0.05). There was a correlation between senior high school girls’ total body LM and LPA ( β =0.063), MVPA ( β =0.601), total body FM and SB ( β =0.029), and MVPA ( B =-0.529)( P <0.05). Conclusion There are gender differences and correlations between adolescent physical activity intensity and body composition. It is recommended that relevant departments provide personalized physical activity dose guidance for adolescents to improve their physical fitness.