The invention discloses an edible biological preservative film and a preparation method thereof. The edible biological preservative film comprises the following components in parts by weight: 30-60 parts of a film former, 1-10 parts of a natural antioxidant, 1-10 parts of a natural bacterial inhibitor, 1-4 parts of a plasticizer and 0.5-4 parts of an emulsifier. The preparation method comprises the following steps: mixing the components in proportion to form preservative film liquid, and preparing the preservative film by adopting a tape-casting process. According to the preservative film, excellent film forming performances of materials such as marine polysaccharides, chitosan, gelatin and the like are utilized, the natural antioxidant and the natural bacterial inhibitor are selected and used, and the modification process is carried out through the plasticizer, the emulsifier and the like, so that the prepared preservative film is good in mechanical property, delays the spoilage of an aquatic product and can effectively prolong the shelf life of the aquatic product.