Microstructures and bonding strength between the treated aluminum alloy and modified polypropylene (PP) were systemically investigated in this study. The results show that an increase in the surface energy of PP by grafting maleic anhydride(MAH) will result in better wetting of the resin on the aluminum alloy layer. The porous microstructures were produced by polishing and anodizing. The interfacial bonding strength of specimens was increased rapidly after anodizing, and the maximum tensile shear strength and work of fracture of P/PAlP specimen reach up to 10.05 MPa and 14.82 KJ/m(2), respectively. The great increase in bonding strength was attributed to porous microstructures and large roughness on the aluminum alloy surface which resulted in resin melt flew into nano holes to from micro mechanical interlocking.