1. A computer-implemented method for encrypting 3D model file, comprising the following steps of: reading data of the 3D model file, the 3D model file comprising a plurality of triangle meshes, the data comprising corresponding coordinates of vertexes of each triangle mesh; selecting at least one triangle mesh and shifting the coordinates of the vertexes of the selected triangle mesh by a vector, wherein the vector is (0, 0, K), and K is a natural number excluding 0; generating a plurality of filling triangle meshes; filling a gap generated from shifting the vertexes of the selected triangle mesh, with the filling triangle meshes, for generating a revised 3D model file; storing the revised 3D model file for generating an encrypted 3D model file.