The Ta-25Ti-18Al-6.5W alloy was prepared by vacuum suspension melting method. The aim of this study was to investigate the oxidation behavior of Ta-Ti-Al-W alloy at 1000℃. The phase composition and microstructure of specimens as-sintered and oxidized were characterized by XRD, SEM, and EDS. It was found that the oxidation kinetics of the alloy followeds the parabolic law at first,and then, changed into the linear law. During the oxidation process, Ta can be oxidized preferentially, and the enrichment areas of TiO2 and Al2O3 were observed in the surface of oxide scale,because of the higher diffusion rates of Ti and Al. In the initial stage,the oxidation was controlled by external diffusion of alloying elements. The oxidation layer mainly composed of the TiO2 and Ta2O5 solid solution of WO3, TiO2, Al2O3. With the increasing of oxidation duration, the oxides scale which controlled the oxidation process shows different layer structure: an outer layer mainly composed of TiO2 and Al2O3, a Ta2O5 solid solution inner layer and a transition layer with less oxygen content.