In the solidification process of the aluminum alloy molten metal, the shrinkage pores are generated due to the shrinkage of the volume or the lack of liquid metal in the final solidified portion. The uneven thickness of the casting or casting is locally overheated, resulting in slower solidification in one part and recessed surface in volume shrinkage. Due to the existence of pores and shrinkage holes, the aluminum alloy die-casting is troublesome for surface treatment. The holes may enter water. When baking is performed after painting and electroplating, the gas in the pores expands by heat, or the water in the pores may become vapor. Volume expansion, resulting in aluminum alloy die casting surface blistering, so in the production of appropriate methods to solve the causes of these defects.