Ti-16.28Si and Ti-15.46Si-5Cu alloys were preparation by high-energy ball milling, cold-pressureless sintering using Ti, Si and Cu powder. The oxidation mechanism of alloys at high temperature oxidation test under 800℃, 900℃, 1000℃ in air were investigated by analyzing the surface and cross-section morphologies and phase composition of sintered and oxidised samples by means of SEM, EDS and XRD. The results show that two kinds of formula samples are mainly containing of Ti, Ti5Si3 and Ti5Si4 phases after sintered, and contain Cu3Si phase of the formula adding Cu; The density increased with Cu added. The main phase of the oxidised samples for 80 h is TiO2, with a small number of SiO2, Ti3O5, TiO, TiN, CuO or Cu2O phases. The oxidation resistance of two alloys reach antioxidant levels at 800℃ and 900℃. For Ti-16.28Si alloy, it possesses the best oxidation resistance at 900℃ with the single rutile TiO2 phase nearly. At 800℃, Cu significantly improves the oxidation resistance of Ti-16.28Si alloy; Compared to Ti-16.28Si alloy, the average oxidation speed is 57.8% of it when the Cu content is 5wt% . However, under 900℃and 1000℃, the oxidation resistance of Ti-16.28Si alloy reduced with Cu added duo to the existing of Cu3Si phase.