Si3N4-Si2N2O composites were fabricated with amorphous nano-sized silicon nitride powders by the liquid phase sintering. The mass loss, relative density and average grain size increase with increasing sintering temperature. The average grain size is less than 500nm when the sintering temperature is lower than 1700°C. Friction coefficient is from 0.35 for sintering temperature 1650°C to 0.74 for 1600°C when the composites were worn by silicon nitride bearing ball. High hardness of 21.5GPa and relative wear resistance of 32 were observed at a sintering temperature of 1600°C. The wear surface are very smooth and no grooving and subsurface fracture, which indicates that they are worn slightly.