The study was to examine the gender differences in aggression among Chinese children after playing violent computer games by using emotional STROOP task. 98 children participated in this study, with 49 assigned to violent computer game group and the other 49 assigned to nonviolent computer game group. The results demonstrated that there were significant differences in main affect of game type, and significant Game Type × Gender interaction as well. In particular, boys’ aggression was significantly impacted by violent games, whereas girls’ aggression was not significantly impacted by violent games. The implication of this research is that, the significant difference in aggression to gender is activated, and that boys were more aggressive and sensitive to violent games than girls.