Si3N4-TiN nanocomposite was prepared by in situ coating in liquid ammonia using TiCl4 and Si3N4 as starting materials. The reduction reaction of TiCl4 by sodium was performed at around - 40°C and resulted TiN nano-powders which nuclei and grew on the surface of Si3N4 particles. The composite powder was consolidated through spark plasma sintering (SPS) at 1600°C and dense compact (>98% of theoretical) with grain size of less than 500 nanometers was obtained. By compositing 20vol. % TiN to Si3N 4. the electrical resistivity of the compact was reduced to small enough value (3.6×10-3Ω·cm) for electrical discharge machining (EDM).