In the research field of online learning, the role of mechanism design is underexplored in terms of finding an effective system design to stimulate user learning and retain users. In this research, using foreign language words-memorizing data from a leading online learning website, we examine two main mechanisms on users’ motivation to learn － user self-imposed deadline and leaderboard listed by the website. We view the words-memorizing progress as a goal pursuit process and depict effects of the mechanisms using prospect theory, framing effect, and social comparison theory. A difference GMM approach is used to address the endogeneity issue. We find that users are less motivated in the middle of the online learning progress (i.e., stuck in the middle). Further, an approaching deadline will stimulate users’ internal motivation to learn more (i.e., deadline rush). Finally, the external motivational effect of leaderboard diminishes as users getting far away from the leaderboard, either above or below. Our results suggest that more incentives should be considered to motivate users when they are in the middle of learning progress, and the principle of displaying leaderboard can be optimized to maximize the effect of social comparison. This study sheds light on the mechanism design of online learning websites. It may also serve as guideline for other goal-involved online settings.