The atomic cluster model of the interface between aluminum oxide film and the niobium matrix has been set up with our self-programmed software. By using recursion method, the atom embedding energy, the atomic binding energy and other electronic parameters have been calculated. The high temperature oxidation mechanism of niobium alloys is analysis from the electron levels. Our study shows that， aluminum segregates on the alloy surface through the grain boundary diffusion and combines with oxygen to form dense Al2O3 oxide film which blocks oxygen to diffuse into the niobium matrix. Grain boundary and rare earth elements can increase binding energy between the oxide film and the matrix and increase the bonding strength of the interface to enhance the adhesion between the oxide film and the niobium matrix. Thus, by adding rare earth elements in the alloy or refining the alloy grains, the performance of high temperature oxidation resistance of niobium alloys can be improved.