The purpose of this study is to investigate the effects of exercise behavior, exercise attitude and exercise knowledge in different genders on health-related physical fitness. 277 college students were served as subjects. Each subject must complete the test of health-related physical fitness and fills out the questionnaire of exercise participation. T-test and stepwise multiple regression were applied to analyze the collected data. The result is as follows: (1) Female students had higher scores on exercise knowledge. (2) Exercise behavior, exercise attitude and exercise knowledge can forecast male students' flexibility, explosive force, strength and muscular endurance, cardio-respiratory endurance on health-related physical fitness effectively. (3) Exercise behavior can forecast female students' body mass index (B.M.I.) and explosive force on health-related physical fitness effectively.