The large virtual reality display system is one of the important equipment of virtual reality display, but the construction experiment of large virtual reality display system has some problems such as high cost and covering a huge area, and therefore it is difficult to conduct training universally. In order to solve such problems, this paper proposes a simulation training system of building a large virtual reality display system based on web3D technology, applying Visual Studio to build web platform, making virtual reality scenes through Max3D and Unity, and using database to record data. This system combines theoretical teaching with simulation practice, and has a relatively complete feedback mechanism for teachers and students. Students can use the mouse and keyboard to simulate and build a large display system in the virtual scene, and integrate the game scoring system to increase the fun of teaching and training. This system can effectively carry out the teaching of building large virtual reality display system at low cost.