Abstract: A pressureless permeating method is put forward. Using a prefabricated porous ferroboron lump, a surface composite layer was made on gray cast iron matrix, with a common casting method. The thickness of the surface layer is 8mm; the hardness and microstructure change gradiently. Sliding wear test shows that the wear resistance of the composite surface is higher than that of Cr12 type high chromium cast iron.