Solid particle erosion on surface of material effects on life time for them such as the turbine brade, boiler tube and chemical processing equipments. Thermal spray is one of various technique which used for the repairing or building up new surface. The objective of this experiment is to study the influence of thermal spray Ni-Si-B coating parameters on the solid particle erosion resistance at room temperature. The coating parameters were the distances between coating nozzle and the substrate of 10, 15, and 20 mm and travel speeds of 1.0 and 1.5 mm s-1 respectively, leading to the difference of heat inputs. The hardness of coating surfaces was measured by Vickers hardness. The microstructure of coating surfaces was examined by using an optical microscope (OM) and scanning electron microscope (SEM). Moreover, solid particle erosion resistance of coating surfaces was investigated on the erosion test rig at room temperature. Erosion rates of specimens were assessed by the calculation of weight loss which measured using an electronic balance (0.1 mg resolution). The relationship between erosion resistance and hardness was studied coincide with the microstructure examination. According to the erosion resistance evaluation, it was found that an erosion rate of coating depended on the coating condition. Finally, wear scar morphology on the top of an eroded surface and cross-section area was observed by SEM. However, the coating parameters played an important role in the erosion resistance. The microstructure of coating concerned with coating parameters was further discussed with the erosion behavior in this research.