Abstract: In the approach proposed in the paper for 3D reconstruction from medical images, we create the auxiliary contour resembling the original contour first, then from outside inwards construct multiple layers of triangles based on the complete contours, and the triangles are linked into tetrahedron finally. By this approach, tetrahedron can be directly constructed from the slice contours, and the method is especially suitable for the 3D medical objects reconstruction based on the slice contour. In comparison with other 3D reconstruction algorithm such as MC, MT, Delaunay tetrahedralization, our approach is simple and easily to be implemented.