Objective To analyze the relationship among body mass index (BMI),fat mass index (FMI),fat-free mass index (FFMI) and athletic ability,and find out the influencing factors of athletic ability,and to provide theoretical basis for the development of appropriate interventions. Methods The height,body weight,sebum thickness,vital capacity,grip strength,speed (50 m run),lower limb explosive force (standing weight long jump) and three-dimensional position flexion.were measured in 4 917 children and adolescents aged 7~18 in Qingdao,who participated in the 2014 National Student Physique and Health Survey.The body fat percentage (BF%) was estimated and the adipose tissue index and non-adipose tissue index were calculated by using the Changling Jinji formula and Brozek formula.The result was analyzed by using correlation analysis and multi-factor linear regression analysis. Results The grip strength was positively correlated with BMI,FMI and FFMI with significant difference.The correlation coefficient between grip strength and FFMI was the highest.The explosive force and muscle strength were negatively correlated with FMI and positively correlated with FFMI.Time for speed run and endurance showed positive correlations with FMI and negatively correlation with FFMI.Multivariate linear regression analysis showed that the effect of height,body weight,chest circumference,waist circumference and FFMI on body mass was statistically significant.The regression coefficient of FMI was -0.128,and it was not statistically significant.The regression coefficient of FFMI was 0.763,which was positively correlated with the total score of physical constitution,with statistical significance. Conclusion Physical exercise,obesity control,body composition improvement,adipose tissue content reduction and non-adipose tissue content increase should be enhanced to improve children and adolescents physical function and exercise quality.