For 35 CrMo test block with different surface hardness,by applying the load spectrum of failure mechanism of actual working conditions,the plastic deformation,surface morphology and internal structure change of surface layer can be obtained under the action of alternating load,and then,the plastic deformation law of 35 Cr o can be obtained.The results show that when the block hardness is low(about 32 HRC),the contact fatigue is mainly cumulative plastic deformation,and the crack depth is shallow(about 10 μm...