Tissue engineering is a kind of cross subject,which develops on the basis of cell biology,molecular biology,bio-material science and clinical medicine.The aim of tissue engineering is to restore and improve the function of scathing tissue using bio-substituent.The basis of tissue engineering is to study and develop the frame materials of bio-substituent.Besides the physical and chemical properties satisfying the growth and reproduction of the seed cell,the materials should hold the following properties,including tissue compatibility,bio-degradability,degradable modulability,nontoxicity,easy to mold.The materials studied extensively are PLA and PGA.The polylacticacids frame materials have been used to be the frame materials of bone,cartilage gristle,blood vessel,nerve and skin.The preparation of polylacticacids and its improvement are reviewed in this article.The application development to tissue engineering is also presented.