Polypropylene with carbon black filler (PP-20%CB) / polypropylene (PP) composites with superimposed conductive layers and insulated layers were prepared by the co-extrusion equipment, and the PPCB normal blends were also prepared. The structure and morphology, conductive properties, mechanical properties and electromagnetic interference (EMI) shielding performance of layer-structure material and normal blend were compared. It is found that the layer-structure composites have better performance in conductivity and EMI shielding effectiveness than the normal blends. The volume conductivity and maximal shielding value of layer-structure composites are 1.96×10³ Ω·cm and 48 dB respectively. While the corresponding values for normal blend composites are 12.53×10⁶ Ω·cm and 28dB respectively. The mechanical measurement indicates that the elongation at break and tensile strength of layer structure composites(654.52%，26.37 MPa, respectively) are also better than those of the normal blend（188.11%，24.78 MPa）.