Abstract: In this paper, the film cracking and propagation of Zinc film/2Cr13 steel substrate system were investigated from experiments and numerical simulations. The crack initiation threshold of Zinc film was detected by the three-point bending test with the acoustic emission technique and the film fracture toughness was calculated. The extended finite element method was adopted to analyze the crack propagation of Zinc film under the three-point bending, and the load-displacement curve simulated by extended finite element method(XFEM) is consistent with the experimental result. Simulation results show that the stress peak occurs in the area of the film crack tip, and the crack propagates when the stress reaches the critical stress of the damage criterion. Meanwhile, the dimensionless energy release rate of period film cracks under various factors was analyzed. It is found that for the same film thickness, when the film crack on a semi-infinite substrate reaches a stable state, the greater the film stiffness is, the greater the substrate thickness and the crack thickness are.