Abstract: When the data volume of the 3D model increases, the model loading speed decreases and the browsing is not smooth. In order to solve the above problems, a 3D model lightweight technology based on the analysis of Cesium's model format 3DTiles is proposed. The texture images in the model are merged according to the material and the model mesh to achieve correct texture mapping and reduce the number of DrawCall calls. The texture and vertices are compressed to reduce the file size of the texture image. Mipmap is used to generate texture images of different resolutions, which is helpful for network transmission. LOD and triangle simplification technology are used to reduce the number of vertices and triangles of the model gradually. According to the complexity of the model, the depth of the octree is adaptively selected to load a certain part of the model on demand so as to reduce the amount of GPU rendering data and improve the smoothness of the 3D scene. Based on the Cesium platform, the frame rate before and after the lightweight processing of the 3D model is tested. The results show that the frame rate is increased after the lightweight processing of the 3D model, which achieves the purpose of efficient loading of the 3D model and smooth browsing.