Abstract: SiCp/Al composites with high volume fraction for electronic packaging were prepared by powder injection molding and pressureless infiltration. The effects of the particle size and volume fraction of SiC on the thermophysical properties of SiCp/Al composites were investigated. The results show that thermal conductivity of SiCp/Al composites increases with the increase of the particle size and volume fraction of SiC. The coefficient of thermal expansion (CTE) of the composites is not affected by the particle size of SiC but depends on the volume fraction of SiC. With the increase in volume fraction of SiC the CTE of the composites decreases, and it agrees well with the predicted values based on Turner's model. By graduation of SiC particles with different sizes, it can be realized that the volume fraction ranges from 53% to 68%. As a result, the CTE(20-100℃) of the composites changes from 7.8×10^-6 to 5.4×10^-6 K^-1, and thermal conductivity from 140 to 190 W·m·K^-1.