Stellite6 coating is cladded on the 17-4PH stainless steel using a diode laser. Fatigue behaviors of substrate specimens, as-cladded specimens and the cladded specimens with heat treatment (550 ℃ for 6 h) are tested with the tension and compression loading method. The fracture surface is characterized by scanning electron microscopy (SEM). The results show that the fatigue strength with 107 cycles of substrate specimens is 470 MPa which is higher than that of the as-cladded specimens with 380 MPa, while the fatigue strength of cladded specimens with heat treatment can reach to 440 MPa. The fatigue surface of substrate specimen shows that the fatigue crack initiates at the surface or inner defects, then propagates forward with the parallel fatigue striations and dimple appearance, while the crack of cladded specimens initiates at the defects in the coating or the interface between the coating and the substrate, then extends to the coating which shows the brittle inter-dendritic fracture and the substrate shows the ductile fatigue fracture respectively.