The solid sintering behavior and mechanical properties of Fe-Ni powders prepared by mechanical alloying of elemental powders and hot pressing sintering in vacuum atmospheres were investigated. It was observed that the microstructure of the powder particles evolves in three stages. The alloy powder with average grain size of 20-30 nm was obtained. The sinter densification depends crucially on the particle rearrangement and the large amount of internal strain introduced during milling. The theoretical density of over 95 % was obtained after hot pressing sintering at 800 ℃ for 30 min with pressure of 50 MPa. No significant grain growth was observed during sintering. And also relatively high hardness was obtained. The solid sintering behavior and mechanical properties of Fe-Ni powders prepared by mechanical alloying of elemental powders and hot pressing sintering in vacuum atmospheres were investigated. It was observed that the microstructure of the powder particles evolves in three stages. size of 20-30 nm was obtained. The sinter densification depends crucially on the particle rearrangement and the large amount of internal strain introduced during milling. The theoretical density of over 95% was obtained after hot pressing sintering at 800 ° C for 30 min with pressure of 50 MPa. No significant grain growth was observed during sintering. And also relatively high hardness was obtained.