The invention belongs to the technical field of machining of medical titanium alloy materials and particularly relates to a preparation method of a titanium alloy bar of a universal resetting screw seat. The chemical ingredients of titanium alloy comprise, by mass percentage, 5.9%-6.4% of Al, 3.9%-4.4% of V, 0.15%-0.22% of Fe, 0.09%-0.13% of O, not larger than 0.05% of C, not larger than 0.005% ofH, not larger than 0.01% of N and the balance Ti. The preparation method comprises the steps that firstly, a round bar blank is obtained through the procedures of smelting, forging, and rolling; thena beta single-phase section homogenization annealing treatment process is adopted to obtain a homogeneous fine-grained acicular martensite structure, an electrifying straightening and hyperbolic straightening combined process is used for straightening, the electrifying straightening temperature is controlled to be less than 780 DEG C, and a balanced residual stress state is obtained; and finally,stress relief annealing and centerless grinding are conducted to obtain the finished bar. The preparation method of the titanium alloy bar of the universal resetting screw seat can produce a medicalTi-6Al-4V alloy bar basically free of stress, the Ti-6Al-4V alloy bar has excellent fatigue life, and a qualified raw material is provided for manufacturing of universal resetting screw seats of orthopedic medical instruments.