The Si3N4- Si2N2O composites were fabricated with amorphous nano-sized silicon nitride powders by the liquid phase sintering(LPS) method. The sintering temperatures ranged from 1500°C to 1700°C. Microstructure and component of the composites were performed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results show that sintered body consists of Si2N2O and β-Si3N4, with an average grain size about 1μm. The maximum value of flexural strength of the material is 680MPa when sintered at 1700°C. Transcrystalline cracking is the main fracture mechanism of the composites.