GH4698 alloy is a precipitation-strengthened nickel-based wrought superalloy with a significant problem of intermediate temperature embrittlement, yet the mechanistic links between heat treatment protocols, microstructural evolution, and mechanical performance remain unclear. This study designed diverse heat treatment regimes and systematically investigated their effects on microstructural evolution and 750°C tensile properties through SEM, EDS, TEM, and mechanical testing. The experimental results demonstrate that multi-stage heat treatment schedules lead to a multi-modal size distribution of γ' precipitates within the alloy, where fine γ' precipitates contribute to strength via dislocation shearing, while coarse γ' phases slightly enhance ductility. At 750 ℃, the alloy subjected to the heat treatment of 1 030 ℃×4 h/AC+1 000 ℃×4 h/AC+875 ℃×16 h/AC+725 ℃×16 h/AC develops a trimodal γ' phase distribution. This microstructure balanced the strength between intragranular and grain boundary regions, facilitating the transfer of dislocation slip and enhancing the ductility of the alloy. The alloy exhibited the best overall mechanical properties, with a tensile strength of 706 MPa and an elongation after fracture of 9%.