Electrical property, as well as the mechanical properties, was observed for the PVC/Al, ABS/Al composites to evaluate the applicability of the composites as an EMI shielding material. The shielding effectiveness (SE) was found to be 30 dB when 20v% of Al filler was added to the polymer matrix, and the volume resistivity was measured as l0⁰-10¹Ω·cm. The tensile strength and the impact strength of the composites with the same polymer/filler ratio were 4×10⁶ Kg/m² and 0.8 J/m², respectively. Those results indicate a future application of the composites to the industrial products as an EMI shielding, such as computer housing et al.. The rheological property was also observed, and the results will provide an important basic information on the processing of the composites when necessary.