Ti70Al30N and graded （Ti, Al）N coatings were deposited on 1Cr11Ni2W2MoV martensitic stainless steel by arc ion plating. Rotary bending fatigue test was conduc ted at room-temperature. The fatigue strength ,fatigue life and fatigue fracture mechanism of the coated samples and the bulk material were compared. The results show that fatigue strength of Ti70Al30N and graded （Ti ,Al）N coated samples increase about seven percent and eight-percent nespectively incomparison to that of the bulk steel. Main reason may lie in the initiation and expansion of the fatigue crack is retarded by the residual compressive stress in Ti70Al30N and graded （Ti,Al）N coatings.