Abstract: Inconel 718 alloy ingots were fabricated by powder metallurgy hot isostatic pressing. Three kinds of heat treatments were carried out on the Inconel 718 alloy ingots, namely solution treatment (holding at 980 ℃ for 1 h and then quenching in water) + aging treatment (holding at 780 ℃ for 8 h and then air cooling), solution treatment (holding at 1020 ℃ for 1 h and then quenching in water) + aging treatment (holding at 780 ℃ for 8 h and then air cooling), and solution treatment (holding at 1020 ℃ for 1 h and then quenching in water) + aging treatment (holding at 720 ℃ for 8 h and then air cooling). The microstructure and mechanical properties of Inconel 718 alloy ingots before and after heat treatment were analyzed by optical microscope, scanning electron microscopes, and transmission electron microscope. The results show that the strength of the hot isostatic pressing Inconel 718 alloy ingots is comparable to that of the forged piece. Due to the presence of the prior particle boundaries, the plasticity of Inconel 718 alloys is weakened to a certain extent, and the overall plasticity level is slightly lower than that of the forged piece. After the solution treatment, some δ phases in the prior particle boundaries dissolve, thereby weakening to a certain extent the detrimental effect of the prior particle boundaries on the plasticity of Inconel 718 alloy ingots. As the aging temperature rises, the γ″/γ′ phase undergoes the excessive aging, resulting in a decrease in strength and an increase in plasticity. The optimal heat treatment is solution treatment (holding at 1020 ℃ for 1 h followed by water quenching) + aging treatment (holding at 780 ℃ for 8 h followed by air cooling).