Polylactic acid (PLA) is a new bio-based and renewable biodegradable material made from starch derived from renewable plant resources such as maize and cassava. Glucose was obtained from starch by saccharification, and then lactic acid with high purity was fermented from glucose and certain strains, and then polylactic acid with certain molecular weight was synthesized by chemical synthesis. It has good biodegradability and can be completely degraded by microorganisms in nature under specific conditions after use, and eventually generate carbon dioxide and water. It does not pollute the environment, which is very beneficial to the protection of the environment and is recognized as environmentally friendly material.