Abstract: Surface quenching treatment of 35CrMo steel was carried out by high power laser. The microstructure, hardness and wear resistance of surface layer under different laser power(1.6,2.4,3.2,4.0 kW) were studied. The results show that when the laser power was 1.6 and 2.4 kW, the undissolved ferrite existed on the surface layer of 35CrMo steel, and the surface layer hardness was lower than that of the substrate; the wear mass rate of the steel was almost the same as that of the substrate after grinding with GCr15 steel, indicating the steel had bad wear resistance. When the laser power was 3.2, 4.0 kW, the surface layer microstructure was all tempered martensite, and the average surface layer hardness reached 640 HV, which was about 20% higher than that after conventional water quenching. The wear mass rate under laser power of 3.2 kW was the lowest, no obvious wear trace could be found on the surface, and the wear resistance was significantly improved compared with the substrate. When the laser power was up to 4.0 kW, the higher self-tempering degree of martensite resulted in a slight decrease in hardness and wear resistance compared with the laser power of 3.2 kW.