【原文】A design method of tangential gradient thermal spraying coating for complex profile workpieces solves the erosion-resistant problem, and obtains a corresponding relation between the ductile-brittle ratio of the thermal sprayed coating and the impact angle change. The method includes: determining the complex profile part surface impact angle change rule according to the part operation environment conditions; selecting an erosion-resistant coating material according to the service condition requirement; obtaining the relation among the impact angle, ductile-brittle angle and erosion rate of the coating by an erosion test; determining the coating and the impact angle ductile-brittle corresponding relation curve; and performing spraying by using dual-channel powder feeding thermal spraying equipment the powder feeding quantity of which is adjustable in real time, based on a matching relation between the tangential gradient coating and the surface impact angle.