The influence of oxygen content on the microstructure and mechanical properties of Ti-23Nb-0.7Ta-2Zr (at%) alloy in as-cast and cold-rolled states was investigated systematically in this paper. It is found that the alloy containing oxygen element is only composed of a single β phase, while the alloy without oxygen element consisted of β and α phases. Although the grain size becomes larger, the elastic de-formation ratio, strength, and hardness of the alloy are all increased with an increase of oxygen content. The as-cast alloy has excellent plastic deformation ability, but the cold-rolled alloy containing oxygen element exhibits brittle characteristics. A conclusion can be drawn that oxy-gen element can stabilize β phase, inhibit the phase transformation from β to α , and furthermore help to increase the strength and elastic de-formation ability of the alloy. The influence of oxygen content on the microstructure and mechanical properties of Ti-23Nb-0.7Ta-2Zr (at%) alloy in as-cast and cold-rolled states was systematically in this paper. It is found that the alloy contains oxygen element is the only composed of a single β phase, while the alloy without oxygen element consisted of β and α phases. While the alloy does not contain oxygen, the elastic de-formation ratio, strength, and hardness of the alloy are all increased with an increase of A conclusion can be drawn that oxy-gen element can stabilize β phase, inhibit the phase transformation from β to α , andצ help to increase the strength and elastic de-formation ability of the alloy.