The invention specifically relates to a heat treatment method capable of improving the notch sensitivity of Thermo-Span alloy, belonging to the field of heat treatment of high-temperature alloy materials. The method comprises the following steps: (1) solid solution treatment: carrying out solid solution treatment at a temperature of 1085 to 1105 DEG C for 1 h and then carrying out air cooling; (2) intermediate aging treatment: maintaining a temperature of 800 to 900 DEG C for 1 to 4 h and then carrying out air cooling; and (3) ageing strengthening treatment: maintaining a temperature of 721 DEG C for 8 h, then carrying out cooling to 621 DEG C in a furnace at a cooling rate of 55 DEG C/h, maintaining the temperature of 621 DEG C for 8 h, and then carrying out air cooling. According to the invention the notch sensitivity of the Thermo-Span alloy can be eliminated through intermediate aging treatment, so reliability of parts prepared from the Thermo-Span alloy can be improved.