The purpose of this study is to investigate the mediating effect of happiness on the relationship between grit and creativity in Chinese middle school students. For the purpose of the study, 287 Chinese middle school students were selected to conduct the survey. Then the correlation analysis was performed to figure out correlations among the variables. According to the procedures Baron and Kenny suggested in 1986, hierarchical multiple regression is conducted to measure the mediating effect of happiness on the relationship between grit and creativity. The results of this study are as follows. First, there was a significant correlation among grit, happiness and creativity. Second, happiness exerts a partial mediating effect on the relationship between grit and creativity. The results suggest that grit as well as happiness can play an important role in increasing middle school students' creativity.