Mental health difficulties affect children and adolescents pervasively. School counsellors serve as frontliners to support the students in need, but often face challenges from the complexity of their cases. This study aims to develop a training module named MDAS (Mental Health disorder, Developmental disorders, Attachment and Self-compassionate) program to improve the school counsellors' mental health knowledge and counselling self-efficacy. The Module was adapted from Child and Adolescent Mental Health Training Module for Specialist 2009 (Second Edition). The study adopted a one group pre-test/post-test design to assess 28 school counsellors at 0-month and 4-month after the training. The scales used were Counselling Self-Efficacy scale (COSE), Mental Health Literacy Scale (MHLS) and Self-Compassionate Scale -- Short Form (SCS-SF). Post-training, there were significant increment of COSE and MHLS scores (p < 0.001 and p < 0.046) with Cohen's d of 1.01 and 0.58. Four of the COSE subscales (micro skills, counselling process, cultural competence and dealing with difficult clients' behaviour) significantly increased after MDAS training (p < 0.001, p = 0.006, p = 0.001 and p = 0.01). In addition to increasing the counselling capacity of school counsellors, our training module can serve as a promising platform for mental health professionals and counsellors.