To take the merits of both wireframe and shaded surfaces, sometimes it is advantageous to combine them together in a single image. However, the combination would often lead to edge stitching and might draw edges that are hidden and the current methods have not so far completely solved the problems since they are mostly based on the Z-buffer comparison. A new method without Z-buffer comparison is presented in this paper. By this method, overlay of edges on shaded surfaces is realized by employment of the correspondence between edges and polygons as well as the hidden relation between polygons. Thus, the existing problems for wireframe overlaying shaded surfaces could be removed, and the calculation for depth values of edges may be saved.