TiN/Ti multi-permeating alloying layer has been formed on the low carbon steel by means of the double glow-discharge plasma surface alloying technique and hollow-cathode effect. The alloying layer was detected by axiovert 25 CA optical microscope with computer analyzing software (LEC), GDA-2 glow discharge spectroscopy (GDS), X-ray diffraction (XRD) and galvanochemical method. The results showed that the thickness of TiN/Ti multi-permeating alloying layer was about 10 μm, the content of Ti on the surface was up to 63.48 wt% and the content of N was up to 12.46 wt%. The atom Ti and N concentrations changed gradually across the depth of the alloying layer and the preferred orientation of TiN/Ti alloying layer was crystal surface (200). The multi-permeating alloying layer and substrate were combined through metallurgy. The surface appearances of the multi-permeating alloying layer were uniform and of a compact cellular structure. The hardness of the surface was about 1600～3000 HV_(0.1). The corrosion resistance of the permeating TiN/Ti alloying layer in 0.5 mol/L H_2SO4 solution was greatly increased and the corrosion rate was only 0.3082 g/m^2·h.
