Abstract: The steel-structure coating in the central and western regions of Inner Mongolia has been severely eroded by sandstorm. Based on the wear test simulating sand erosion to the steel-structure coating, the eroded surfaces of the coating at different erosion conditions were observed by using scanning electron microscopy and the erosion mechanisms were analyzed. A formula for assessing the erosion degree of the coating was proposed. Results show that erosion was mainly micro-cutting at low erosion angle and erosion resistance is mainly determined by the hardness. Erosion was extrusion deformation at high erosion angle and erosion resistance was mainly determined by the toughness. Because the coating in this study had low hardness and good flexibility, the erosion resistance of the coating was good at high erosion angle. Mass loss of the coating due to erosion was the highest at the erosion-angle of 45° because the erosion wear characteristic of a brtittle-ductile the material was observed. Higher speed which meant higher kinetic energy of particles generated higher erosion loss. At a low sand dose, the eroded wear of coating increased with increasing sand dose, while at a high sand dose, the result is the opposite. The calculated results from the proposed formula was in good agreement with the experimental results.