Abstract：This study investigates the influence of avatar figure on users' health cognition and health behavior. 128 college students were randomly assigned to the obese avatar group or the normal avatar group, and manipulated the avatar to live a day in The Sims 4. The results show that, compared with the normal avatar group, the obese avatar group spent more time engaging in healthier activities and made healthier choices for meals in the virtual environment. After the game, the self-efficacy on physical activity of this group also improved. These results validate our hypothesis: the obesity characteristics of the avatar may promote exercise and diet-controlling behavior by indirectly activating the user's goal representation.