Abstract: The PS45 coating was fabricated on 20 steel substrate by high velocity arc spraying process. Microstructures,resistance to high temperature oxidation and thermal shock were studied by means of scanning electron microscopy(SEM) and X-ray diffraction(XRD). The results showed that the prepared coatings were compact and the interface between the coating and the substrate was convex and concave,which meant the bonding property was good. The coating was composed of spreading zone and splash zone produced by deposited particles. XRD results showed that the coating mainly consisted of δ(Ni-Cr),Ti O₂ and Cr₂ O₃. The oxidation weight increase of coatings at 750℃ was more obvious than that at 550℃ and 650℃. After 15 thermal cycles,coatings did not appear obvious phenomenon of cracks and spalling at 550℃. Oxides of Ni O,Cr₂ O₃ and Ni Cr₂ O₄ generated after the coating being oxidized.