Abstarct: Physical activity is the cornerstone of a healthy lifestyle. Regular and organized exercise and physical activity are an effective factor in the development of health, vitality and happiness of all sectors of society. The joy and joy of adolescents, which constitute a huge body of society, will ensure the future health of the community. The purpose of this study was to predict the company's adolescents in sports activities baxsed on the theory of planned behavior. The statistical population of this study was all male and female students of the first and second grade of the city of Damghan (3426 people), among whom 206 were selected by cluster random sampling and were sampled. To determine the validity and reliability of the questionnaire, the Theory of Planned Behavioral Aggression (1986) was used. To determine the face and content validity of this questionnaire, four supervisors of sports management were consulted. To determine the reliability of the questionnaire, a preliminary study was conducted on 30 students in Damghan city. The results of Cronbach's alpha test indicated that the questionnaire had acceptable reliability (attitude = 0.78) (mental forces = 0.75) (perceived behavioral control = 0.81 ) (Intention = 0.82) (behavior = 0.76). To test the hypotheses, Kolmogorov-Smirnov test, Pearson correlation and structural equation modeling were used. The results showed that attitude and perceived behavioral control of adolescents had a positive and direct effect on their intention to participate in sports activities, but abstract adolescents' norms did not have a significant effect on their intention to participate in sports activities. On the other hand, perceived behavioral control of adolescents has no significant effect on their behavior in sporting activities. If the intention of adolescents has a positive and direct effect on their behavior in participating in sports activities. Finally, with respect to the values obtained from the fitness indexes, the pattern is well-suited to explain and fit, and the indicators indicate that the model is in line with the observed data.