Abstract: Si powders with average particle sizes of 75 μm and 48 μm respectively and mass fraction from 0% to 8% were added to the SiC ceramic materials which were sintered at 1550℃ for 3 h. The effects of particle size and addition amount of Si powder on sintering properties, mechanical properties and microstructures of SiC ceramics were studied. The results show that the addition of Si powder with different particle size and content can improve the microstructure of SiC ceramic material and improve its sintering and mechanical properties. Within a certain range, the smaller particle size of Si powder is more conducive to the formation of uniform and compact SiC sintered body, and greatly improves the performance of SiC ceramic material. When the particle size of Si powder is 48 μm and the mass fraction is 4%, the sintering and mechanical properties of SiC ceramics are better, whose volume density and apparent porosity are 2.58 g/cm³ and 13.5% respectively, with flexural strength and hardness 25 MPa and 115 HRB respectively.