The annealing treatment of plastic products refers to the plasticization unevenness of the plastic in the cylinder or the uneven cooling rate of the product in the cavity, which causes the internal stress of the product to cause deformation, cracking and aging of the product in the future. The annealing treatment is carried out indoors, using a hot liquid medium such as hot water, hot mineral oil, hot glycerin, etc., to a temperature 20-35 degrees higher than the product use temperature or 25-35 degrees lower than the heat distortion temperature of the product. Next, the product is placed in, the length of annealing depends on the wall thickness of the product, and the thicker the wall, the longer it takes to anneal. It should be noted that the annealed product should be flattened to allow it to cool naturally after taking out the hot liquid. It is not possible to use the cold water to take the quick cooling method. Annealed products are generally PC, PS and other plastics, for POM, PVC and other plastics do not need to be annealed.