A music teaching system based on virtual reality technology can virtualize teacher resources and teaching environment resources. Through the unique immersion, interactivity and conceptualization of virtual reality technology to create the environment needed for music learning, thus making the use of resources more convenient. This paper constructs a music teaching system that includes teaching content and teaching form, music teaching system, and teaching evaluation system. Among them, the music teaching system allows online instruction, virtual environment learning, and human-computer interaction. In order to create a good simulation environment, lightweight deep reinforcement learning method is proposed for the problem of high requirements of deep reinforcement learning training resources in virtual resources, and a deep separable convolutional deep reinforcement learning model is designed. Compared with the deep reinforcement learning model, this model can obtain a higher reward value when the learning rates are all 0.001, and is more suitable for the construction of the simulation environment of the music teaching system. After the teaching practice for freshmen majoring in music in S school, the comprehensive evaluation score of teaching effect is 84.29, which indicates that the teaching system designed in this paper can ensure the quality of music teaching.