Aggression is a prevalent problem and negatively affects the mental health among Chinese college students. Trait anger has been found to be a risk factor for aggression, but little is known about the factors that may explain or influence this association. The current study aimed to explore the relationship between college students' trait anger and aggression, as well as the mediating role of anger rumination and the moderating role of internal and external locus of control. In this study, the Trait Anger Scale, Anger Rumination Scale, Internal--External Locus of Control Scale, and Aggression Questionnaire were administered to 1018 college students. The results showed that the trait positively predicted anger rumination and aggression. The mediating effect of anger rumination between trait anger and aggression was significant. Also, Internal and external locus of control plays a moderating role in the second half of the mediating model, and as the level of an individual's internal and external locus of control increases, the predictive effect of anger rumination on aggression gradually weakens. These results suggest that the effect of trait anger was mediated by anger rumination and moderated by internal and external locus of control.