At present, due to the acceleration of the urbanization process, the mental health problems of rural left-behind children are increasingly prominent, which are manifested as increased loneliness, emotional loss, insufficient learning motivation and social obstacles. Aiming at this social pain point, through systematic empirical research, this study analyzed the unique role of music, as an art form of non-verbal communication, in promoting emotional expression, relieving psychological pressure, improving social skills and cultivating positive emotions for left-behind children. By using questionnaire survey, in-depth interview, experimental intervention and effect evaluation, the study selected a number of rural left-behind children as sample points, designed and implemented a series of music-based psychological counselling activities, such as music listening, music creation, choir and musical instrument learning. The research results show that left-behind children who participate in music activities have significant improvement in anxiety and depression, self-confidence and self-efficacy are significantly enhanced, and parent-child communication and social integration are promoted, showing a more optimistic attitude towards life. This study not only enriched the theoretical system of mental health intervention for rural left-behind children, but also provided a practical music therapy path, and provided a scientific basis and reference model for the government, schools and social organizations to formulate and implement mental health support projects.