NOVELTY - Producing proathocyanidin oligomers involves: degreasing cypress grape seed cake, passing by meshes sieve, while adding acid in water; adding enzyme (0.2-1 mass%) including tissue protease and pawpaw protease in mixed solution for enzymolysis; using film vibration filter system, by utilizing energy and micro-filtration membrane where interception molecular weight material of 5x 103 is not passed through, and nano-filtration membrane that separates liquid of 300 molecular weight; and concentrating and drying separated liquid, where content of proanthocyanidins is more than 95%.    USE - For producing proathocyanidin oligomers by biological enzymatic method (claimed), useful for eliminating active oxygen free radicals, and in health care field to form food, medicine, and cosmetic products.    ADVANTAGE - The method is simple to operate, fast, green and pollution-free, easy to industrialize, and produces oligomeric proanthocyanidins of high quantity. The use of film vibration filter system for producing oligomeric proanthocyanidins, solves problem of static membrane filtrating method, in which membrane is easily blocked, and difficult to clean. The method prolongs service life of the membrane.    DETAILED DESCRIPTION - Method for producing proathocyanidin oligomers by biological enzymatic method involves: degreasing cypress grape seed cake to obtain raw material, passing by 80-100 meshes sieve, in which sieve is added with 6-22 mass times of acid at pH of 3-6 in purified water to obtain mixed solution; adding enzyme in mixed solution, where mass content of mixed enzymatic solution is 0.2-1% to carry out enzymolysis for 30-120 minutes at 35-50 degrees C, where mass ratio of mixed solution to enzyme is 1:0-0.8, and enzymes include tissue protease and pawpaw protease; using film vibration filter system, by utilizing energy and micro-filtration membrane where interception molecular weight material of 5x 103 is not passed through, and nano-filtration membrane that separates liquid of 300 molecular weight; and concentrating and drying separating liquid obtained, where obtained content of proanthocyanidins is more than 95%. For degreasing cypress grape seed cake raw material is passed by 90 meshes sieve, and to sieve is added 10-15 mass times of acid of pH of 4-5 and purified water to obtain mixed solution. The mass content of mixed enzymatic solution is 0.5%, enzymolysis is carrying out for 60-80 minutes at 40-45 degrees C, ad mass ratio of mixed solution to enzyme is 1:0.3-0.5.