Si3N4 ceramic matrix composites toughened with TiC nanoparticles were fabricated by using hot pressing technique with Al2O3 and Y2O3 as sintering aids. The effects of hot pressing temperature on the densification, mechanical properties and microstructure of Si3N4-TiCnano composites were investigated. The experimental results showed that optimum mechanical properties were achieved for Si3N4-30vol. % TiCnano composite hot pressed at 1750°C for 60min, under 30MPa pressure in N2, with the flexural strength, fracture toughness and hardness being 850MPa, 6.7MPa×m1/2 and 16.5GPa respectively. The microstructure and phase composition of the composites were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The analysis results indicated that fine, elongated b-Si3N4 grains and the reinforcements of both intergranular and intragranular TiC nano particles as well as the sub grain boundaries inside the b-Si3N4 grains contributed to the optimum properties of the composite hot pressed at 1750°C.