Abstract: Chitosan is obtained by N-deacetylation of chitin, which is extensive, nontoxic and readily biodegradable.It has good adsorption capacity for heavy metal ions because there are a lot of functional groups such as amino and hydroxyl in its structure. It is available to enhance the stability and selective adsorption of chitosan by appropriate modification. In this article, chitosan modification methods were reported. The application of chitosan and its derivatives in food industry was summarized and its use in heavy metal removal from shellfish extraction was reviewed.