In light of the ongoing COVID-19 pandemic, mental health concerns have become more prevalent worldwide. However, there is a lack of research specifically addressing the mental well-being of college art students. Therefore, the purpose of this study is to examine the prevalence of depressive symptoms among college music students and explore the factors that predict and alleviate these symptoms amidst the challenges posed by the COVID-19 pandemic. An online survey was conducted among college music students (n = 407) from two universities at May 2022 in China. Self-report scales were used to measure levels of depression (Zung Self-Rating Depression Scale), positive childhood experiences (Benevolent Childhood Experiences Scale), social support (Multi-Dimensional Scale of Perceived Social Support), and regulatory emotional self-efficacy (Regulatory Emotional Self-Efficacy Scale). Hayes PROCESS macro for SPSS was used to test the hypothesized effects of regulatory emotional self-efficacy and social support in the relationship between positive childhood experiences and depression. Results showed that, the prevalence of depression symptoms of the current study sample was 64.13%, positive childhood experiences had a significant and negative predictive effect on the depression of college music students, and the relation was partially mediated by regulatory emotional self-efficacy. Furthermore, social support moderated the relationship between positive childhood experiences and regulatory emotional self-efficacy, the relation was significant only for students with higher levels of social support, social support may enhance and amplify the positive impacts of positive childhood experiences on regulatory emotional self-efficacy. The findings reveal a significant prevalence of depression among college music students during the COVID-19 epidemic, underscoring the seriousness of the issue. Moreover, this study contributes to a deeper comprehension of how positive childhood experiences alleviate depression among college music students. These insights hold potential for informing mental health education initiatives tailored to college art students in the post-pandemic era, offering valuable guidance for promoting their well-being and resilience.