Polylactic acid (PLA) is a new biodegradable and renewable biodegradable material, made from renewable plant resources (such as corn, cassava, etc.) made of starch. Starch raw materials through saccharification to obtain glucose, and then from the glucose and a certain strain fermentation into high purity lactic acid, and then through chemical synthesis method to synthesize a certain molecular weight of polylactic acid. It has good biodegradability, and can be completely degraded by microorganisms in nature under certain conditions after use, and eventually generate carbon dioxide and water, which does not pollute the environment, which is very beneficial to the protection of the environment, and is recognized as an environmentally friendly material.