The present invention discloses a high-temperature and high-strength titanium alloy and a preparation method thereof, and belongs to the technical field of titanium alloy materials. The high-temperature and high-strength titanium alloy comprises, by weight, 6.0-7.0% of Al, 2-4% of Sn, 3.5-3.8% of Zr, 0.2-0.5% of Hf, ] 0.3-0.8% of Ta, 0.5-1.5% of W, 0.2-0.5% of Si, and the balance of Ti, wherein the sum of Zr and Hf is 4%, and the sum of Nb and Ta is 1.5-3%. According to the present invention, vacuum self-consumption electric arc furnace melting, cogging, middle forging, rolling, and annealing or solution aging treatment are adopted to obtain the titanium alloy with the tensile strength of not less than 720 MPa at a temperature of 650 DEG C, the tensile strength of not less than 580 MPa at a temperature of 700 DEG C, and the lasting breaking time of not less than 30 min at 700 DEG C/350 Mpa; and the high-temperature and high-strength titanium alloy meets the application requirements on the titanium alloy under the short-term high-temperature and high-strength conditions.