Along with scientific and technological advancement,polymer materials are beginning to be broadly applied in modern medical science,called biomedical polymers. There are currents that bio-degradable materials will be the mainstream in the development of biomedical polymers. Poly lactic acid (PLA) is a kind of excellent biomedical poly-ester,which has good biocompatible feature and can completely degrade into H2O and CO2. It started to be highly anticipated as a kind of promising degradable biomedical polyme...