Introduction: Restricted and repetitive behaviours (RRBs) is one of autism spectrum disorders (ASD) core criteria. Exhibitions of RRBs produce profound implications on the functional aspect of these children and family. Evidence found that RRBs is related to the reward system dysfunction in the basal ganglia of these children. RRBs induces intrinsically rewarding effects on children with ASD. Listening to music was found to influence the reward system on the typical population and also discover to be promising as complementary strategies for ASD. A study found that high functioning adolescents with ASD cognitively stimulated through listening to happy music. Planning inter-vention for RRBs by looking towards the mechanism of reward system function remained unexplored. The primary objectives of this study is to examine the effect of happy music on RRBs symptoms. Methods: This study will use a randomised control trial research design with pre-test and post-test assessments in 20 children with ASD. Two parallel randomly assigned group will undergo twelve weeks of intervention sessions. The experimental group will listen to happy music and engage in free play sessions. For the control group, they will engage in free play session only without the music. Parents will complete the Repetitive Behaviour Scale-Revised, which consists of 6 subscales on RRBs to measure the outcome of the study. Results: The study will compare the RRBs between two groups. Con-clusion: Outcome of this study may set forth further investigation on the management of RRB using non-aversive contemporary approach.