The advantages of PLA are as follows: first, the raw materials are easy to be recycled and suitable for large-scale intensive production; Second, the permeability, transparency and hardness, tensile and bending modulus can be comparable to the traditional plastic resin; Third, better biocompatibility. Its monomer raw material l-lactic acid is an endogenous active substance in human body. Therefore, PLA products are non-toxic and non-repellent to human body, and can be absorbed by human body. It can be made into medical tissue skeleton material and medical carrier and used in human body safely. Fourth, it is completely degradable. Buried in the soil for 6 to 12 months can be degraded into carbon dioxide and water.