With the booming of performing arts in China, which is obviously embodied in the increasing number of performances and audiences, and the requirement of performance quality is increasing. Therefore, a virtual choreography system becomes particularly important with great value and significance. This paper aims to explore and develop a virtual choreography system for medium-scale and large-scale performances. By doing research on the key technology of the virtual choreography system based on WebGL, we put forward a series of methods including file compression, preloading, embedded server and v8 engine optimization, which can help assure the smooth operation of the system. Meanwhile, we adopt WebGL to achieve the creation and rendering of three-dimensional models so that users can directly complete the whole process of large-scale rehearsals in the system. It has great prospect.