Abstract: The effect of the salt bathing nitriding under different temperature on the microstructure of Martensite stainless steel and the change of hardness and wear ability under different treatment temperature are comparatively studied. The study results show that when 17-4PH stainless steel was subjected to the salt bathing nitriding, the main items in the nitrided layer are the expanded（nitride contended） martensite（α'）, Fe_2-3（N, C）, CrN, Fe₄N and Fe₃O₄. The amount of Fe₃O₄ and CrN was increased with the treatment temperature going up. The lattice constant of expanded martensite has the similar change. The activation energy of nitriding in this salt bath was 190.9kJ/mol. The depth of the nitrided layer was increased with the treatment temperature increasing.After the alloy nitriding at 580℃, the mass loss in the slide wear test was reduced from 21.1mg for H1100 condition to 1.0mg.