Abstract: The habitual behavior and implementation intention into the theory of planned behavior(TPB)was studied to be a model of extended TPB(METPB)and this model was tested with moderate to vigorous physical activity(MVPA)of adolescents aged 9~19 years.The differences in the prediction of METPB of MVPA were examined among primary, secondary and high school students. It is founded that the model of hypothesized relationships demonstrated a good fit with the data, and the METPB has a higher predictive ability than the TPB model, after including habitual behavior and implementation intention.The findings revealed that attitude and perceive behavioral control is significantly associated with MVPA intention, which explained 31.4% variance of intention.Behavioral intention and implementation intention are significantly associated with MVPA behavior, which explained 18.7% variance of behavior.Implementation mediated the influence intention on behavior.There is a significant difference in the influence of METPB variables on MVPA of adolescents in primary, secondary and high school students. Subjective norm is significantly associated with MVPA intention of primary and middle school students instead of high school students.The stronger association between perceived behavioral control and MVPA behavior goes with the higher learning stage.The government, school, and parents should put emphasis on the improvement of adolescent attitude towards PA, intention to participate in PA, and PA habit to promote adolescent PA participation. The differences among primary, secondary, and high school students should be taken into consideration when designing intervention.