Abstract: A simplification method considering geometric characteristics of BIM model is designed aiming at deficiency of traditional geometric simplification in BIM models. The proposed method gets the surface geometry data of BIM model firstly, and judge whether it is a triangular patch according to the number of vertices of a grid in BIM model. When the polygon is triangular, it is simplified by merging triangular patches, and the boundary line of the merged polygon is simplified by three-point method. According to the principle of short edge, the vertex of the adjacent polygon is moved to the opposite edge. The simplified model is given the corresponding material attributes based on the grid division according to the obtained material information. The proposed method can quickly simplify the triangular patches and boundaries of BIM model geometric data, and retain the advantages of original geometric features of BIM model by judging the shape after merging.