This study investigated whether child abuse was associated with psychiatric co-morbidity in a group of Chinese adolescents, and whether this association would be mediated by emotional processing difficulties and moderated by the severity of PTSD from other traumas in the past. Four hundred seventy-four adolescents participated in the study. They completed the Childhood Trauma Questionnaire-Short Form, General Health Questionnaire-28, the Posttraumatic Stress Diagnostic Scale, and Emotional processing scale-25. The results showed that after adjusting for the total number of traumatic events and how long ago the most traumatic event occurred, child abuse was associated with psychiatric co-morbidity. This association was not moderated by the severity of PTSD from past traumas but mediated by emotion processing difficulties. To conclude, adolescents who experience child abuse can develop emotional processing difficulties which in turn impact on psychiatric symptoms. Experience of past trauma does not influence these psychological processes.