Effects of different melting temperatures (270 and 210 degrees C), Al flake widths (0.5 and 0.8 mm), and coupling agents (gamma aminopropyl triethoxy silane A1100 and gamma glycidoxy propyl trimethoxy silane A-187) on the properties of ABS + 20%PC/Al flake-metallized plastics are discussed. According to experiments, it is found that the aspect ratio is larger with the 270 degrees C melting temperature and 0.8 mm Al flake, but declines with the A-187 coupling agent. The 0.5 mm Al flakes treated with the A-1100 coupling agent at 270 degrees C melting temperature has better distribution in the matrix and EMI shielding effectiveness, but has a lower volume resistance. With 0.8 mm Al flakes at 210 degrees C melting temperature, and treatment with the A-1100 coupling agent, it produces larger ultimate tensile strength and impact strength. There is no relation between HDT and melting temperatures, Al flake widths, or coupling agents.