Restrained eating refers to consistent, cognitively mediated efforts to restrict eating for the purpose of weight control. Research shows that dietary restraint not only can result in feelings of inadequacy and anxiety, but also may play a causal role in the onset of eating disorders such as bulimia and binge eating, disturbances that have significant negative implications for individual’s health and functioning. According to studies in both China and abroad, the prevalence of eating disorders among younger groups was very high. Investigation and research of adolescent girls found that about 50% of the respondents reported dieting behaviors and the female undergraduates have become high-risk groups of restrained eating. Therefore, restrained eating behavior of female undergraduates should be paid more attention by researchers. In the past few years, researchers have shown increasing interest in self-objectification, because it has been demonstrated that self-objectification was an important predictor for restrained eating, but the mechanism need to be further studied. In recent years, social networking site (SNS) has become an indispensable social tool for college students, and it has an important effect on individual’s physical and mental development, therefore, the study of female undergraduates’ eating behavior should also consider the role of SNS. Some empirical studies have also indicated that body image comparison on SNS might play an important role in the relationship between self-objectification and restrained eating. In addition, previous researches showed that effortful control has a potential protective effect on adolescents’ bad behavior. As an important personality trait, effortful control may affect the way individuals process information of self-objectification and body image comparison on SNS, thus alleviating the negative effects of self-objectification and body image comparison on SNS. Therefore, the present study aimed to examine the mediating role of body image comparison on SNS and the moderating role of effortful control in the effect of self-objectification on restrained eating. To conclude, the present study constructed a moderated mediation model and used it to explore the relationship among self-objectification, body image comparison on SNS, effortful control and restrained eating. A survey research method was adopted in which Self-Objectification Questionnaire, SNS Appearance Comparison Scale, Effortful Control subscale and the Revised Restraint Eating Scale were administered to 487 female undergraduates. The results indicated that: (1) Self-objectification was positively correlate with body image comparison on SNS and restrained eating, and body image comparison on SNS was also positively correlated with restrained eating, effortful control was negatively correlate with self-objectification, body image comparison on SNS and restrained eating; (2) Self-objectification could affect restrained eating through the mediation effect of body image comparison on SNS; (3) Both the direct effect of self-objectification on restrained eating and the mediation effect of body image comparison on SNS were moderated by effortful control, and both these two effects were much stronger among female undergraduates with low effortful control. The study uncovered the complex mechanism between self-objectification and female undergraduates’ restrained eating behavior. Self-objectification influenced female undergraduates’ restrained eating behavior, both the direct effect and the mediation effect of body image comparison on SNS were moderated by effortful control.