Effects of sintering temperature, hot isostatic pressing（HIP）and heat-treatment on the microstructure, density and mechanical properties of Inconel718 alloy prepared by metal injection molding were investigated. The results show that the sintered alloy with a relative density of 98% can be achieved at 1275 °C. After HIP process, full density was achieved. After heat-treatment, a large amount of γ″ and γ′ phase were precipitated which increases the tensile strength and decreases the elongation of the alloy. The tensile strength and elongation were 1250 MPa and 21.7%, respectively, at room temperature, and 1177 MPa and 16.6% at 650 °C respectively, which are comparable with or superior to those of the wrought alloy.