The nitrosulfurized layer and wear property of gas nitrosulfurized alloy steels were discussed. A test pieces of SNC 631, SCr 430 and S45C steels were treated in an atmosphere of the 50%NH3, 0.02%H2S and propan converted carrier gas mixture in the temperature of 843 K for 10.8 ks. It was confirmed by X-ray diffraction that the main surface products were Fe1−xS, FeS, Fe3N and Fe4N at each specimens. The compound layer was observed on the cross sectional microstructure of treated specimens. The hardness of compound layer was become hard in the order of S45C, SNC 631 and SCr 430. The wear test was carried out under the condition of 490 kPa using pin-ring system wear tester without lubrication. It was found that the gas nitrosulfurizing of steels were improved wear resistance of steels because the compound layer which was formed on the treated specimens was reduced the adhesion of the sliding plane and those effect was remarkable on the alloy steels.