GH4706 alloy is used for industrial gas turbine disks owing to its excellent properties, including high creep resistance, tensile strength, toughness, and microstructural stability up to approximately 650 ^oC. However, the increasing weight and size of large turbine disks have limited the cooling rate following the solution treatment, which hinders the control of the microstructure and mechanical properties of large GH4706 alloy disks. Herein, four solution post-treatments were conducted on a 1500-mm-diameter disk manufactured from GH4706 alloy after being treated at 980 ^oC for 4 h: air cooling + air cooling (AA), furnace cooling to 825 ^oC and stabilization treatment followed by air cooling (FSA), furnace cooling to 825 ^oC followed by air cooling (FA), and furnace cooling to 825 ^oC followed by asbestos cooling (FAs). The evolution of precipitates during aging (including for γ'/γ" coprecipitation and η phase) and their effects on mechanical properties were analyzed. Results indicated that reducing the cooling rate from 980 ^oC to 825 ^oC promoted the precipitation and growth of the η phase, leading to Ni and Ti consumptions. This inhibited γ'/γ" coprecipitation around the large η phase, thereby favoring the formation of a cellular microstructure. Further reduction in cooling rate from 825 ^oC to 600 ^oC substantially accelerated the growth of γ'/γ" coprecipitates into cubic forms. The volume fractions of the cellular microstructure in the FSA, FA, and FAs treatments were 4.1%, 1.0%, and 1.8%, respectively. The AA and FA treatments had negligible effects on the tensile properties of GH4706 alloy at room temperature; meanwhile, the FSA treatment slightly decreased tensile ductility. The FAs treatment led to a notable reduction in yield strength at room temperature. In impact testing at room temperature, the cellular microstructure accelerated crack initiation and propagation, resulting in a 64% lower impact toughness of GH4706 alloy for the FSA treatment compared to that for the AA treatment. However, during stress rupture testing at 650 ^oC, the cellular microstructure effectively hindered crack propagation and the growth and aggregation of micropores, thereby extending the rupture life. However, the FAs treatment reduced the rupture life due to strength loss caused by the large γ'/γ" coprecipitates. The FA treatment fostered an optimal level of cellular microstructure, thereby increasing the rupture life while maintaining excellent tensile and impact properties at room temperature, demonstrating remarkable overall mechanical properties.