Si3N4-based composite ceramic tool materials reinforced with TiC0.5N0.5 particles were fabricated by using hot-press-sintering technique with Al2O3 and Y2O3 as sintering aids. The effects of the content of TiC0.5N0.5 on the microstructure and properties of composite ceramic were investigated. The experimental results show that optimal mechanical properties were achieved for the composite with the addition of 20 vol.% TiC0.5N0.5 microparticles, with the flexural strength, fracture toughness and Vicker's hardness being 838 MPa, 8.5 MPa•m1/2 and 15.6 GPa. The fracture surface microstructure of the composites is characterized by scanning electron microscopy (SEM). Phase identification was carried out by X-ray diffraction (XRD). It was found that the microstructure of the material was homogenous and the elongated grain of β-Si3N4 was interlaced. And the fracture surfaces were observed to exhibit a mix of intergranular and transgranular fracture.