Abstract: As the second largest natural polymer substance in nature, chitosan has been widely used in food, medicine, environmental protection, industry, cosmetics, textile and other fields. In food processing, chitosan can inhibit the growth of microorganisms in aquatic products, so it is often used in the preservation of aquatic products. However, when chitosan is used alone for fresh-keeping, it has the characteristics of low oxidation resistance and poor sensory quality, so other substances are often added for compound fresh-keeping in practical application. Biological preservative is a new preservative extracted from nature or obtained by using biological engineering technology. It has the characteristics of high efficiency and green. Therefore, in recent years, the technology of chitosan combined with other biological preservatives to keep aquatic products fresh has attracted extensive attention of researchers. Therefore, the preservation properties and mechanism of natural chitosan were described, and the application of chitosan and other biological preservatives in the preservation of aquatic products was reviewed. The existing problems were analyzed and the possible solutions were put forward. Meanwhile, the development prospect of chitosan compound biological preservative in the preservation of aquatic products was prospected.