Objective To study the effect of TiN/ Ti coating structure on equivalent plastic strain of TC4 titanium alloy after impact. Methods By using the finite analysis software ABAQUS, a 2D axisymmetric finite element model was established for the impact between spherical particle and TC4 substrate coated by TiN/ Ti costing. The effects of hard layer thickness and hard layer number on the equivalent plastic strain of substrate were analyzed. Results Plastic strain of uncoated substrate occurred only during the loading stage of impact. Coating divided the plastic strain response of substrate into two parts, loading and unloading. For the single layer coating, when the thickness of the hard layer was less than 12 μm, the increased hard layer thickness oscillated the plastic deformation of substrate. When the thickness of the hard layer exceeded 12 μm, the increased hard layer thickness reduced the plastic deformation of substrate. For the multi-layer coating, when the thickness of hard layers was remained, the increased number of layers can reduce the plastic deformation of substrates. Conclusion In conclusion, finite element simulation can be used to investigate the erosion behavior of TC4 titanium alloy with TiN / Ti coating, optimize the architecture of TiN / Ti anti-erosion coating, and has guiding significance of architecture design and further research on anti-erosion coatings.