Abstract: Firstly,Ni-50Cr alloy coating was prepared by high velocity arc spray (HVAS) on 20G steel substrate.The high temprature oxidation resistance of the coating was compared with that of 20G steel and Tafa 45CT coating at 750 ℃.Optical microscopy (OM),scanning electron microscopy (SEM) and X-ray diffractometer (XRD) and X-ray energy dispersive spectrometer (EDS) were used to analyze the microstructure and oxidation produce of the coatings.The results show that the microstructure of Ni-50Cr coating was the typical layer structure.Compared to 20G steel and Tafa 45CT coating,the high temprature oxidation resistance of Ni-50Cr coating was increased by 85 times and 1.3 times respectively.NiO,Cr2O3 and NiCr2O4 were identified as the main phases of the oxidated coatings.As the increasing of Cr content,the Cr2O3 content in the protective oxide scales was gradually increased,which resulted in a significant enhancement of the high temperature oxidation resistance.