Achievement goal theory is a prominent social cognitive theory of motivation, and it is an advanced problem of achievement goal study. Recently, researchers divide achievement goal into four types in the study field: mastery approach goal, mastery avoidance goal, performance approach goal, and performance avoidance goal. Social comparison was that the individual compared his character quality, standpoint and behavior with those of others. It is a common social psychological phenomenon for human being. Academic self-efficacy is the representation of self-efficacy in academic field, reflecting the individual’s academic ability faith. A series of previous studies have investigated the role of achievement goal, social comparison, and academic self-effect separately, and some of which further examined the relations between the two variables as mentioned above. There are few studies, however, to investigate the relations among all the three variables. In the present study, we examined the relations among the achievement goals, social comparison and academic self-efficacy, especially to investigate the mediating effect of social comparison between the relationship of achievement goals and academic self-efficacy. There are three scales mentioned in the current study: Achievement goals Orientation Scale with four dimensions (mastery approach goal, mastery avoidance goal, performance approach goal, and performance avoidance goal), the parts of Iowa-Netherlands Comparison Orientation Measures including upward comparison and downward comparison, and Academic Self-Efficacy Questionnaire composed by the self-efficacy of learning ability and learning activity. 847 questionnaires were sent out to 4 junior high schools in Hunan Province, and 724 of which have been recovered, with the valid recovery rate of 85.48%. There were 336 males and 388 females. All of data was analyzed by the software of SPSS 15.0. Correlation analyses showed that the master approach goal and performance approach goal positively correlated with upward comparison, learning ability self-efficacy and learning activity self-efficacy, and negatively correlated with downward comparison. Secondly, there were another two negative correlations as follows: the master avoidance goal negatively correlated with study behavior self-efficacy, and the performance avoidance goal and downward comparison negatively correlated with academic self-efficacy. Furthermore, the performance avoidance goal positively correlated with downward; and upward comparison positively correlated with academic self-efficacy. The mediating analyses showed that the relations among master approach goal, performance approach goal and study ability self-efficacy were mediated by upward comparison partially; otherwise, downward comparison not only mediated with the relations between performance approach goal and study ability self-efficacy partially, but also mediated among master approach goal, performance approach goal, performance avoidance goal and study behavior self-efficacy. As described above, we argued that, for junior school students, their achievement goals had an effect on their academic self-efficacy with a direct way. Besides, the academic self-efficacy was affected by the achievement goals indirectly as well.