The electrical property of MMC is essentially important to some applications such as power transmission lines and cables, electronic and electrical components as well as electromagnetic shielding equipments. The behavior of electrical resistivity of SiC w /Al alloy composites under as-extruded and annealed conditions has been investigated within the temperature range from room temperature to 450 ? C . It can be seen that within entire temperature range, the electrical resistivity of composites was higher than that of an unreinforced matrix alloy under the same condition of either as-extrusion or annealing. The temperature dependence of both exhibited positive incline like a typical metal. The variation of electrical resistivity of an unreinforced matrix alloy with temperature from ambient temperature to 450 ? C was nearly monotonous, while those of composites increased monotonously at low temperature and rose to a high level after about 250 ? Cor275 ? C . The difference of these temperature dependences on electrical resistivity can be interpreted as qualitatively the interfaces of SiC w fibers and matrix, where act as nucleation sites.