To realize the mesh simplification in the three-dimensional(3D) reconstruction of medical images,a method based on 27 neighborhood-grids is proposed for the establishment of the topology of a triangle mesh.First,the marching cubes(MC) algorithm is used for extracting 3D volume data from a set of CT image sequences and converts a group of 2D images into consisting of a set of triangular facets the 3D model.Then a mesh topology of the 3D model is established by using 27 neighborhood-grid algorithm.Finally,the topology of 3D model is simplified with the quadric error metric(QEM) algorithm for dynamic visualization of medical image.The reconstruction system is built with Visual C++ software and OPENGL library.The results of 3D reconstruction show that the computational efficiency of this method is superior to that of the traditional method of loop iterations.Compared with the traditional method,it is simple and fast,and the computational complexity increases linearly with the amount of data.