▎ 摘　　要

NOVELTY - Preparing biopolymer composite film, comprises (i) dispersing the biopolymer in the solvent and preparing polymer solution, where the solvent is preferably water or polar solvent; and (ii) coating the polymer solution on the surface of the microporous substrate to form wet film, drying to obtain the biological polymer composite film, where the biological polymer is lignin salt, starch, carboxymethyl cellulose, gelatin, pectin, collagen, isolated soy protein, chitosan and derivatives, alginate, polyacrylic acid, polyethylene oxide and polyvinyl alcohol resin for forming a film layer with barrier property but selectively permeable to water molecule. USE - The method is useful for preparing biopolymer composite film. ADVANTAGE - The film can block other substances i.e. gas and has good biological compatibility, and wide application prospect. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for biopolymer composite film, is prepared as mentioned above.