In this paper the gradient surface-alloying layer similar to superalloy Inconel 625 is obtained at the surface of three kind steels (low carbon steel, industrial pure iron, stainless steel 304) by using Double Glow Plasma Surface Alloying Technique. These gradient superalloy surface alloying layers are formed by high temperature diffusion of alloy elements at Double Glow Plasma Surface Alloying. The chemical composition of surface layer can be controlled by source electrode material and technological parameters such as power of source electrode and cathode and processing times etc. The microstructures analyzed by XRD show that the alloying layer consists of gamma matrix and some precipitates (Laves intermetallic phase etc.) which depends on the local area composition. The corrosion resistance of nickel base surface alloying layer has been investigated by electrochemical method in 3.5%NaCl and 5%HCl solution. The results indicate: the corrosion resistance of surface alloying layer formed at pure iron substrate is better than that of nickel base superalloy Inconel 625. The results of 200 h exposure tests in 20%H2SO4 and 20%HCl solution show that the corrosion rates of surface alloying layer on pure iron are also equal to that of nickel base alloy Inconel 625 and one order of magnitude lower than that of AISI304 stainless steel.