Abstract: This study introduced a behaviour theory—Four Steps from Inactivity to Activity(FIT) model,which is lately developed by German and Chinese exercise psychologists targeting adults' physical activity process of change.Meanwhile,the questionnaire of adults' physical activity based on the FIT model was also evaluated preliminarily.The results revealed that FIT model could systematically describe the stage characters of physical activity process of change among Chinese and German adults.In addition,it also demonstrated health status factors as well as social,psychological and environmental determinants which are regarded as essential catalysts for transitions between the stages.It was verified that the questionnaire had reached acceptable psychometric level by reliability and validity test in Chinese and German samples.Sequential empirical studies should be carried out in the future to promote the development of FIT model in China and in Germany.