Background: TGT (three good things) exercise is one of the positive psychological interventions. Previous studies found that recording three happy things with their reasons every day can effectively reduce the symptoms of depression, improve the level of well-being and mental health. It has been found that college students (especially postgraduate students) have a high level of anxiety and depression. In addition, the intervention method of combining TGT practice with social network (QQ group) helps to improve the mental health of HIV-infected patients. Objective: In order to examine the intervention effect of TGT exercise on postgraduate students, and to test whether the "three good things" exercise based on Wechat social platform can improve postgraduate students’well-being. The study explored the effect of TGT from quantitative and qualitative aspects. Methods: In this study, three groups of designs were adopted: the TGT group, the TGT-SN group (social network three good things, TGT-SN; complete the three good things exercise through the WeChat platform) and the control group (no practice, the WeChat administrator posted the psychology related materials). 232 postgraduate students were recruited from a university in Beijing. Participants voluntarily chose to join three groups (133 in TGT-SN group, 53 in TGT group, and 46 in control group). The TGT intervention lasted forty days, and participants’ well-being, depression, interpersonal relationship, and intervention quality were evaluated before intervention, after intervention immediately, and one month after the intervention. Results: The 40-day intervention was completed by only 150 participants (TGT-SN group 77, TGT group 40, control group 33). The loss of subjects was large and the compliance rate was low. Even if the participants knew that TGT exercise was beneficial to the body and mind and voluntarily participated in TGT exercise, they were still lack of motivation and difficult to adhere to it. The results showed that there was only a continuous improvement in depression scores (F (2, 125) = 3.20, p = .01, partial η 2= .05), but no positive effects were found in well-being, life satisfaction, positive emotion, and interpersonal relationship scores. Combined with the quality evaluation of the intervention effect, the subjects reported that the TGT exercise is effective, and that Wechat is suitable as a mental health intervention platform.They also prefer to choose TGT intervention exercise based on Wechat social platform, which can increase the motivation of practice. The reason why the effect of TGT exercise is not significant might be due to the multiple effects of research design, external emotional events, cultural differences and so on, and frequent daily practice will only increase the burden and reduce the exercise execution, and exercise three times a week is more beneficial to the practice effect. Conclusion: People can benefit from readily available, simple, well-being-enhancing interventions, so that future research needs to improve the TGT practice procedure to overcome the problem of people's own executive ability (knowing good but not doing).