The invention discloses a thermal treatment method capable of enhancing the high temperature strength of a Ti2AlNb-based alloy. The thermal treatment method comprises the steps of pretreatment, solution treatment, quenching, aging treatment and detection of tensile strength, wherein in the pretreatment process, a thermal treatment test sample is subjected to ultrasonic cleaning, and cleaning fluid is acetone; in the solution treatment, a plate material is placed into a box type resistance furnace for the solution treatment at the temperature of 1,150 DEG C, and the temperature is preserved for 1 to 1.5 hours; in the quenching process, the quenching transferring time is 2 to 5 seconds; in the aging treatment process, the Ti2AlNb-based alloy is put into the box type resistance furnace for the aging treatment at the temperature of 770 to 790 DEG C, and the temperature is preserved for 2 hours; and after the aging treatment is completed, air cooling is carried out. According to the thermal treatment process, the high temperature tensile strength of the Ti2AlNb-based alloy is enhanced; at the temperature below 950 DEG C, the tensile strength reaches 180 MPa and is enhanced by 37 percent; and furthermore, the Ti2AlNb-based alloy has a uniform microstructure and can meet the requirements of the aviation and aerospace field for material performance.