How to improve users' health management performance is an important challenge for practitioners of digital health platforms. Gamification is considered a potential method to encourage individuals to engage in health management and improve the level of their health management performance. To better understand the role of gamification in the health management context, this study investigates the influence of the achievement mechanism on the health management performance, as well as the moderating effects of social network and health condition. This study collected 1554 users’ data (54.4% female and 45.6% male, age: 18–35) from an online health community in China and built a regression model combined with the U test estimation algorithm to examine the research hypotheses. The results of the empirical model show an inverted-U relationship exists between level of achievement and the level of health management performance. Moreover, our research shows that the size of the social network and the health condition negatively moderate the inverted-U relationship. These findings facilitate an understanding of the role of gamification in the health management context. Further, the study contributes to goal setting theory and provides new insights and suggestions for users and designers of health management platforms and online health communities.