Chitosan has special physicochemical properties such as short-term biodegradability, biocompatibility with human tissues, antibacterial and antifungal activity and non-toxicity, so it has high potential in various industries. In addition, biological properties such as bioadhesion, anti-cancer, antimicrobial, anti-inflammatory and analgesic, antioxidant, blood coagulant and cholesterol-lowering distinguish it from other biological polymers. It has been used as a safe compound in drug formulations for more than a decade. Different samples of chitosan can be prepared with different molecular weights as well as different degrees of deacetylation. In this way, it took advantage of the multi-stage de-acetylation process. In this case, the reaction temperature, reaction time and number of reaction steps are considered as effective parameters. Molecular weight and percentage of deacetylation play a decisive role in the biological properties of chitin, chitosan and their derivatives. So far, various derivatives of chitin and chitosan have been obtained. By manipulating the extraction steps (removing mineral and protein compounds), higher purity derivatives can be prepared. In other words, changes in the structural properties of the material are very effective on the final characteristics of the product.