Integrating online and offline teaching is a new direction for the new energy vehicle testing and maintenance technology professional course, which is conducive to improving the limitations of teaching venues and facility conditions. In this paper, the two paths of optimizing the collision algorithm and designing the virtual simulation teaching software achieve online-offline integration teaching. In order to optimize the authenticity of the operation of automotive parts in virtual simulation teaching, a distributed enveloping box collision detection algorithm is proposed, and the parts that need to be accurately gridded for collision are screened by the OBB algorithm, so as to improve the performance of collision detection. Design virtual simulation teaching software using text, video, sound, and other multimodal information for online and offline integration. The experiment shows that the optimized collision detection algorithm has good performance, and the experimental class score is 6.33 points higher than the control class, indicating that the fusion of online and offline teaching modes has an obvious effect.