High-temperature oxidation resistance in static air of 0Cr18Ni9Ti stainless steel (substrate for short), and the substrates after treated respectively by hafnizing process, hafnizing carburizing process were investigated. The results show that: Thickness of Hf-alloyed layer is 35 um, the layer found continuous and dense with no holes, combined with the matrix as a metallurgical bond, the surface phase is Hf2Fe, HfC, Hf; Thickness of Hf C layer is 100 um, and dispersively distributed many granular and short rod carbide particles which size 1 ~ 2um, the main types are MC, M7C3, M23C6. The oxidation rate of Hf-alloyed sample in 1050℃ and 1100℃ are just 1/3, 1/8 that of substrate, and Hf C layer sample about 1/8, 1/25, the oxidation rate increases as the temperature rises, the rate and oxidation mass is Hf C layer sample < Hf-alloyed sample < substrate, and the oxidation mass comply with the parabolic law; The surface alloying elements reduced, Hf increased after hafnizing and carburizing successively, and surface flaking improved, oxidation defects reduced and holes turn smaller, Hf can solidify the surface oxide layer and improve solid solution strengthening, carbide particles as HfC and oxides as HfO2 can reduce the rate of diffusion of oxygen ions, improved oxidation resistance significantly.