The link between empathy and aggression is well documented; yet, studies examining potential mechanisms that explain this association are limited. In the present study, we tested the relation between empathy and aggression and examined both the mediating and moderating effects of moral disengagement on this relation among Chinese male juvenile delinquents. Three hundred and fifty-seven male juvenile delinquents from one Chinese juvenile correctional facility completed the interpersonal reactivity index, the moral disengagement scale and the aggression questionnaire. The results indicated that moral disengagement partially mediated the influence of empathy on aggression. Moreover, moral disengagement moderated the relation between empathy and aggression. Specifically, there was a significant negative relation between empathy and aggression at low levels of moral disengagement. However, at high levels of moral disengagement, the relation between empathy and aggression was non-significant. The significance and limitations of the results are discussed.