Objective: To explore the relationship between sedentary behavior with cardiorespiratory fitness and executive function in adolescents, and to provide some references for sedentary behavior prevention and executive function improvement. Methods: From September to December 2022, a total of 5 018 adolescents aged 13 to 18 years were selected by stratified random sampling method in Shanghai, Suzhou, Taiyuan,Wuyuan, Xingyi, and Urumqi to conduct physical activity survey, as well as cardiorespiratory fitness and executive function assessment. Pearson s correlation was used to analyze the relationship between sedentary behavior, cardiorespiratory fitness and executive function. The mediation effect model was fitted by the bootstrap mediation procedure in the PROCESS (version 3.3 ) SPSS macro compiled by Haves, and the mediation effect of adolescents cardiorespiratory fitness in the relationship between static behavior and executive function was examined using model 4 in the PROCESS SPSS macro, where Boosrap method was used to compute the mediation effect of adolescents cardiorespiratory fitness. where the Boosrap method was used to calculate confidence intervals for the mediating effects. Results: Adolescents daily sedentary time was positively correlated with both the refreshing function (1-back and 2-back) and the switch function reaction time ( r =0.05, 0.07, 0.05, P <0.01). Adolescent VO 2max was negatively correlated with both the refreshing function (1-back,2-back) and the switching function ( r =-0.09, -0.14 , -0.11, P <0.01). Adolescents daily sedentary time was negatively correlated with VO 2max ( r =-0.04, P <0.01); cardiorespiratory fitness mediated effect values between sedentary behavior and refreshing function (1-back and 2-back) and converted function were 0.20(95% CI =0.06-0.36), 0.43(95% CI =0.14-0.74) and 0.13 (95% CI =0.04-0.22), with mediating effect shares of 6.87%, 8.33% and 8.59%, respectively. Conclusion The duration of sedentary behavior in adolescents is related to executive function performance, and cardiorespiratory fitness may serve as a mediator to mediate the association between sedentary behavior and executive function in adolescents.