Abstract: Solid solution treatment from 920 ℃ to 1 060 ℃ for 1.5 h and aging treatment from 650 ℃ to 850 ℃ for 6-10 h were carried out on Inconel718 alloy, the effects of solid solution temperature, aging temperature and aging time on microstructure and mechanical properties of the alloy were studied. At last, a appropriate heat treatment process was obtained. The results show that, comparing with solid solution, the hardness of the alloy was obviously improved after aging treatment. With the increase of solid solution temperature, austenite grain grew and δ phase dissolved gradually. The suitable solid solution temperature was 1 000-1 020 ℃. With the increase of aging time, dispersion strengthening of precipitated phases in the alloy was better, and yield ratio increase signally. After solid solution treatment at 1 000-1 020 ℃ and aging treatment at 750 ℃ for 10 h, the mechanical properties of the alloy was optimum, tensile strength,impact absorption energy at room temperature and hardness was more than 1 200 MPa, 120 J and 310 HV10, respectively.