Abstract: The simplification scheme for triangulation net formed by a lot of 3-D scattered data points is discussed. Removing faces plan is employed for the mesh simplification algorithm. Some simplification criterions of triangulation net are introduced, with the emphasis on the calculation method for the simplification weight based on the normal vector of triangles. Meanwhile, the criteria of re-triangulation during the simplification of triangulation net are put forward, and the re- triangulation method based on the side expanding is presented.