The invention discloses a thermal treatment method of TC4-DT titanium alloy. The thermal treatment method is specifically implemented according to the following steps that step 1, a preheating stage is carried out, wherein a forged rod material of the TC4-DT titanium alloy is preheated at 900-960 DEG C, and then is cooled to the room temperature; step 2, a first annealing stage is carried out, wherein the rod material of the TC4-DT titanium alloy obtained in the step 1 through cooling is heated to 984-1009 DEG C, heat preservation is carried out for 1-2 hours, and then the heated rod materialis cooled to the room temperature; step 3, a second annealing stage is carried out, wherein the rod material of the TC4-DT titanium alloy obtained in the step 2 through cooling sequentially undergoestreatment of heating, heat preservation, and cooling to the room temperature for at least one time. According to the thermal treatment method, the tissue structure and the mechanical property of the TC4-DT titanium alloy can be effectively improved, and the guidance is provided for the heat treatment of the TC4-DT material through the thermal treatment method; and according to the thermal treatment method, the tissue performance of the TC4-DT material can be adjusted within a certain range so as to obtain tissues and performance which meet different requirements.