The invention discloses a lightweight visualization method of building information model based on Web3D. By parsing the EXPRESS language description file which defines the IFC standard, the method ofextracting all kinds of information from the IFC file is established, and the information for 3D visualization is extracted at the same time. Through the transformation of geometric expression and thecalculation of rotational position matrix, the original 3D visualization information is transformed into the rendering data which can be rendered by a WebGL graphics engine. Then, combined with the building shape characteristics, the original multi-branch tree algorithm is improved to create a hybrid index based on building indoor and outdoor space partition and multi-branch tree forest. Finally,based on the hybrid spatial index, using the technology of view elimination, occlusion elimination, multi-threading and cache management, in the WebGL-based three-dimensional interactive graphics application, the rapid scheduling of three-dimensional model data between the browser and the server is realized. This method has the advantages of good lightweight performance, cross-platform and high computational efficiency.