The invention relates to the field of hot working of high-temperature alloys, in particular to a heat treatment method for controlling an IN718 alloy to uniformly separate out a delta phase. The heattreatment method comprises the following processing steps that (1) the to-be-treated IN718 alloy is subjected to heat preservation at 1020 DEG C or above, and then water cooling to the room temperature; (2) the treated alloy in the step (1) is subjected to the heat preservation at 700-900 DEG C; and (3) the alloy treated in the step (2) is subjected to the heat preservation at 900-1000 DEG C and then air cooling to the room temperature, so that the delta phase is obtained. By changing a precipitation mode of the delta phase, a gamma phase is separated out firstly and then is converted to the delta phase instead of being directly separated out of austenite, so that the delta phase is uniformly distributed at a crystal and a grain boundary, and the segregation at the grain boundary of the delta phase is improved.