42CrMo was treated with soft nitriding salt bath process,and the effect of complex salt bath treatmenton hardness of 42CrMo was analyzed.The tribological characteristics of 42CrMo with complex salt bath treatment was studied under different lubrication conditions and load,and the mechanism of friction and wear.The results indicate that the average hardness of 42CrMo with soft nitriding salt bath treatment is increased from HV310 to HV74733,which is about 25 times as much as the untreated alloy.With increase of load,the friction coefficient of 42CrMo under dry friction is increased first and then decreased,while they are increased constantly under boundary lubrication and oil lubrication.The friction coefficient,the depth of surface grinding crack and wearing capacity of 42CrMo under boundary lubrication and oil lubrication are decreased obviously compared with that under dry friction.The wear mechanism of 42CrMo is serious adhesion wear and plastic deformation under dry friction.The surface wear slow down under boundary condition,which only has a slight furrow,while the surface occurs abrasive wear and there is no obvious deformation under oil lubrication.