Social comparison is the process of evaluating oneself in comparison with others. People actively or passively, consciously or nonconsciously engage in social comparison. Upward comparison---comparing to better off others, engenders psychological inferiority, while downward comparison---comparing to worse off others, elicits psychological superiority. The purpose of the current research was to explore how such psychological inferiority and superiority information resulted from social comparison would influence others-oriented behavior, namely, prosocial behavior. We postulated that downward comparison could increase people’s empathy towards others, and thus would promote prosocial behavior. Two studies were conducted to test the hypotheses. In Study 1, undergraduates were randomly assigned to the upward comparison, the downward comparison, and the control conditions. In the upward (downward) comparison condition, participants were asked to compare their academic performance with the classmate whose academic performance was ranked the first place (last place) in their major. In the control condition, information aboutacademic performance or comparison was not mentioned. After making the comparison, participants indicated their willingness to help in four hypotheticalscenarios. Empathy, self evaluation, and emotion were measured. In Study 2, we used donation intention as an indicator of prosocial behavior. Rather than asking participants to consciously make upward or downward comparison as in Study1, we manipulated social comparisonbygivingfalse intelligence test feedback. All participants completed a subset of Raven intelligence test. Participants in the upward comparison condition were told that their performance in the test was ranked the bottom 10% of our population. Participants in the downward comparison condition were told their rank was in the top 10%. Those in the control condition did not receive any feedback about the test score. Then we asked participants to read two scenarios and indicate their willingness to donate. Empathy was also measured using the same scale as in Study 1. Results of Study 1 indicated that as compared to the upward comparison condition and the control condition, participants in the downward comparison were more likely to help others. There was no significant difference between those in the upward comparison condition and the control condition. Empathy, rather than emotionorself evaluation, acted as the mediator of this effect. Study 2 further replicated this result, and suggested that those who knew they were better than others showed higher empathic concern for people who needed help, which in turn increased donation intention. In conclusion, downward social comparison would promote prosoical behavior by increasing people’s empathy towards those who need help. This effect was not driven by positive emotionnor enhanced self evaluation, but was mediated by the empathetic feeling.