Using Unity3D, WebGL technology, OpenGL technology and 3D simulation technology, the project of virtual simulation experiment of bridge technical condition assessment was developed based on the identification of bridge engineering disease threshold control index. The virtual simulation experiment teaching system fully covers the whole process of preview, implementation, review and examination of the experiment, and realizes virtual and real combination. This system can solve the problem of difficulty in review and examination of disease detection operation caused by the limitation of cost, safety risk and schedule arrangement in single entity experiment. At the same time, the problems such as the difficulty in reproducing the spatial distribution position of the highway bridge components and the poor teaching effect in evaluating the technical condition are solved. In addition, the system can enhance the students' perceptual understanding of the relationship between the parts in the engineering space and the standardized operation process of bridge engineering inspection and technical condition evaluation before entering the real engineering site. The virtual simulation experimental system realizes the integrity, efficiency, green, environmental protection of the experimental project, and the examination of the whole experimental process.