Self-control is a well-known inhibitor of aggression, but the effect of self-control on different kinds of aggression (such as reactive–proactive aggression) and the underlying mediating mechanisms of these effects are unclear. We developed a mediation model to address these issues. A three-wave study was conducted with a sample of 1203 qualifying Chinese undergraduates to test the model. The results showed that self-control at Wave 1 negatively predicted reactive aggression at Wave 3 through mediating effects of hostile rumination and moral disengagement at Wave 2 at the same time, while self-control at Wave 1 negatively predicted proactive aggression at Wave 3 only through moral disengagement at Wave 2. Furthermore, the longitudinal relationship between hostile rumination and moral disengagement is mutual. The current findings support our hypotheses regarding the mediation model of self-control inhibiting reactive–proactive aggression and suggest that moral disengagement should be a common and basic variable to predict most kinds of aggression; further, hostile rumination only has a particular effect on reactive aggression. The present study used motivation theory to explain its mediation model, which develops aggressive theory regarding varied common influencing factors and underlying mediating mechanisms of reactive and proactive aggression.