Poly (lactic acid) (PLA) is a new type of biodegradable material, which is made from starch, a renewable plant resource such as corn. The raw material of starch is made into lactic acid by fermentation, and then converted into polylactic acid by chemical synthesis. It has good biodegradability. After use, it can be completely degraded by microorganisms in nature, and eventually generate carbon dioxide and water, which does not pollute the environment. It is very beneficial to protect the environment and is recognized as an environmentally friendly material. We are responsible for caring for the earth. According to news reports, the global temperature will rise to 60 ℃ in 2030. The common plastic treatment method is still burning and cremation, resulting in a large number of greenhouse gases discharged into the air, while the polylactic acid plastic is buried in the soil for degradation, resulting in carbon dioxide directly into the soil organic matter or absorbed by plants, which will not be discharged into the air, causing no greenhouse effect.