The invention relates to a preparation method of a titanium alloy spring made of a wire with a specially-shaped section and belongs to the technical field of springs. The spring is formed by winding of the titanium alloy wire with the specially-shaped section; the titanium alloy wire comprises the components in percentage by mass as follows: 2-4 of Al, 6-10 of V, 4-8 of Cr, 2-6 of Mo, 2-6 of Zr, 0.1-0.3 of Fe, 0.03-0.15 of Si and the balance of Ti. The section of the titanium alloy spring wire can be rectangular, square, orthohexagonal or oval. The titanium alloy wire wound into the spring is prepared with forging, pressing and hot rolling technologies, the wire is subjected to solution treatment before being wound into the spring, and a finished product of the spring is subjected to aging and strengthening treatment. A titanium alloy which is used for preparing the spring can play a weight reduction role, and meanwhile, the titanium alloy has the good corrosion resistance and the long fatigue life in an ocean environment. With the adoption of the wire with the specially-shaped section, the section area can be increased under the condition that specifications of wires are similar, so that the rigidity of the spring is improved, and the usage requirement of the titanium alloy spring under the high workload can be met.