Abstract: The SiC_p/Al composites with SiC volume fraction of 30%, 40% and 50% were prepared by powder extrusion forming. The microstructure, mechanical properties and physical properties of different SiC_p/Al composites were analyzed by optical microscopy, scanning electron microscopy, tensile tester, brinell hardness tester, thermodilatometer and thermal conductivity detector. The results showed that 30% and 40% SiC_p/Al composites could be extruded in 450℃, but 50% SiC_p/Al composite failed. On longitudinal section of composite, the aluminum matrix was distributed along the extrusion direction and presented the white strip streamline structure. The tensile fracture surface of two composites was made up of a large number of smaller dimples, both of which presented mixed fracture characteristics. With increase of SiC_p volume fraction, the brinell hardness increased from 81.9 HB to 98 HB while tensile strength decreased slightly and the elongation reduced obviously. The relative density and coefficient of linear expansion of the composite reduced while thermal conductivity improved.