By use of first-principles calculations based on density-functional theory, the stability of low-index surfaces of Al3V intermetallic were analyzed, then the adsorption of oxygen on Al3V surface and the effects of alloying elements were studied with the most stable surface. The results show that Al-terminated (110) surface is the most stable. The adsorption of oxygen at brige sites of the surface are preferable, and the adsorption of oxygen are more and more stable as the coverage increases. It can be inferred from DOS analysis and the distance between O and other atoms that at the initial stages the oxidation of Al atoms and internal-oxidation of V atoms occurred, that means the protecting Al2O3 scale can be formed after oxidation. Ti and Cr atoms prefer to substitue V atoms in 2nd layer, the substitution of the atoms can both improve the adsorption stability of oxygen on the surface, while the mechanisms are different. The interactions between Ti and O atoms are strong, so the interactions between Al and O atoms are weakened after Ti substitution, that means Ti and Al can both be oxidized to form mixed oxides. On the other hand, the interactions between Al and O atoms are slightly enhanced after Cr substitution, so the oxidation of Al atoms are improved, that means the protective Al2O3 scale can be formed.