The invention relates to a metastable beta-type Ti- Nb-Ta-Zr-O alloy and a method for preparation, wherein the components of the alloy are that Nb is 35-38 percent by weight, Ta is 0-3 percent by weight, Zr is 2-4 percent by weight, O is 0.2-0.8 percent by weight, and the other content is Ti. The method comprises V1ing, the Ti- Nb-Ta-Zr-O alloy whose components are uniform is obtained through the vacuum consumable electrode arc furnace melting method. V2ing, Ti- Nb-Ta-Zr-O alloy ingots are done by heat processing treatment in the temperature range of 800-100 DEG C. V3ing, after being done by the solid solution quenching treatment, the Ti- Nb-Ta-Zr-O alloy which is treated in the temperature range of 1000-1200 DEG C is cooled, thereby obtaining a single-phase beta tissue. V4ing, solid solution state Ti- Nb-Ta-Zr-O alloy is done by cold processing treatment in room temperature, thereby obtaining various alloy bars and plates. The alloy of the invention has super elasticity, low modulus, high strength, no biological toxicity, corrosion resistance, excellent biocompatibility and easy processing forming, and the alloy is capable of being widely used on biological implantation materials and other medical devices.