In China, graduate students are facing heavy pressure from study, work and life. In order to change this situation, many colleges and universities have set up PE elective courses, but the proportion of elective courses is generally low, and the health status of students has not been fundamentally improved. The purpose of this study is to investigate the current situation and motivation of Postgraduates' physical exercise, and explore ways to attract more postgraduates to participate in physical exercise and promote their health. The study mainly adopts the methods of experiment and questionnaire. Two classes of students who chose PE elective courses are selected as the experimental objects. Students in Experimental class were given motivation stimulation, while another class were not. Sports stimulation includes combing family health history, inculcating the role through cases, monitoring students' physique, etc. The two classes had same exercise time (once a week, 90 minutes each time), same exercise method (intermittent cycle training for 16 weeks). In addition, this study uses Professor Chen Shanping's sports motivation scale to conduct a questionnaire survey on the graduate students participating in the experiment. Pearson analysis method in SPSS software was conducted to analyze the correlation between sports motivation and sports behavior. The students in the experimental class exercise better after class than those in the control class. Girls' physical and social motivation of physical exercise is much higher than boys, while boys' ability and motivation of physical exercise are significantly higher than boys. Different physical exercise motives have significant effects on physical exercise methods and physical exercise frequency. It is concluded that motivation stimulation is conducive to the formation of exercise behavior and there is a positive correlation between physical exercise motivation and physical exercise behavior.