Objective To improve the thermal spraying coating layer. Methods Composite layer was prepared by using multipass friction stir processing technology. The transformation regulation of microscopic structure, element diffusion and microhardness were analyzed both on the affected area coating layer and substrate. Results A composite layer of uniform density and fine crystallization, interface of coating layer and substrate disappeared, dynamic recrystallization occurred was formed. A 260 μm hierarchical gradient affected zone was formed from the coating layer to the substrate: BZ, RLS, FRZ, ECZ. The coupling effect of temperature and plastic deformation provided favorable channel to fast element interdiffusion. Combination of fine-grain and elements diffusion obviously improved the microhardness and mechanical performance. Conclusion Friction stir processing technology can effectively improve the microscopic structure and properties of thermal spray coating layer.