The SiC/6061 composites were produced by powder metallurgy method, with the SiC particle volume fraction being 20%, 25%, 30% respectively. The microstructures of the materials were observed by Optical Microscope. The tensile strength and Coefficient of thermal expansion (CTE) were examined. Turner and Kerner theoretical models were employed to analyse the CTE. The influences of the SiC particles volume fraction on the microstructures and performances were analyzed. The results show that with the increase of the SiC particles volume fraction in the composites, the clustering degree of the SiC particles increases in the matrix, and the CTE decreases which is close to the average of the Kerner and Turner theoretical model predictions, and the tensile strength increases but when the volume fraction of SiC particles exceeds the critical value of 30% the tensile strength of the composite decreases. And the strengthening mechanism of experimental materials was discussed.