Chitosan and sodium alginate are two prominent biomaterials because they have some unique properties such as good biocompatible and biodegradable. In this study, sodium alginate was as swelling and moisture retention layer; Chitosan was antibacterial layer.Polylactic acid (PLA) blended in different weight ratios with low melting point polylactic acid (LMPLA) to fabricate nonwoven fabric which reinforced by needle punching and hot pressing. Afterward, chitosan/ sodium alginate compound solution were treated by UV light in order to form cross-linking. Then chitosan/ sodium alginate compound solution coated on the PLA nonwoven fabric to make PLA composite dressings. The mechanical properties of chitosan/ sodium alginate membrane and dressing were measured. The optimum parameters of chitosan/sodium alginate composite membrane was treated by UV light for five minutes and the volume ratio of chitosan (3 wt %) and sodium alginate (1 wt %) solution was 8:2. After we coated chitosan/sodium alginate solution on PLA nonwoven fabric, the Tensile strength, and tear strength were upgraded by 80 % and 98 %; its air permeability and flexibility length, however, dropped by 18 % and 60 %, respectively.