Numerous studies have linked aggression during childhood with long-term maladjustments and anti-social behaviour. Despite the alarming rise of aggression and violence in Hong Kong, few studies have been conducted on anger control intervention. It is well-known that aggression hinders development in children and creates numerous problems in the family, school, and community. The researcher reviewed the aetiology of childhood aggression from the ecosystemic perspective, and implemented an indigenous Anger Coping Training (ACT) programme for children aged 8-10, with physically aggressive behaviour and for their parents. Based on cognitive-behavioural therapy, the parent-child parallel group ACT program involved experimental and control groups with pre- and post-comparisons. Quantitative data collection consisted of the Child Behaviour Checklist (CBCL), Child Behaviour Checklist Teacher`s Report Form (CBCL-TRF), and Peer Observation Checklist (POC). Meanwhile, two pilot studies were conducted prior to the main study. Eighteen out of 34 applicants were selected and divided into two experimental groups and one control group using the rule of randomization. There were no significant differences in the pre-treatment scores, and none of the demographic variables were statistically different among the three groups. The effectiveness of the ACT program was consistent. In post-intervention and follow-up studies, the treated children showed a consistent reduction in their physically aggressive behaviour. However, there was no obvious decline in their verbally aggressive behaviour. The research aims to contribute insights and practical help to parents, social workers, and teachers concerning childhood aggression in Hong Kong.