Abstract: Chitosan are abundant polysaccharides in nature, which play many important roles in food, medicine, agriculture, environmental protection and other fields. The deacetylation degree of chitosan is also one of the most important indexes to evaluate their performance. Therefore, the convenience and accuracy of deacetylation degree detection method are highly required in application. In this paper, the chemical analysis methods, spectral analysis methods, destructive analysis methods and electrical characteristics analysis methods are summarized, and the advantages and disadvantages of various methods and their improvement schemes are discussed. It is found that chemical analysis and spectroscopy have not only good detection results, but also a wider range of applications, while electrical characteristics analysis methods have broad prospects for development. The antibacterial and fresh-keeping ability of chitosan with a high degree of deacetylation is valued, while chitosan with a low degree of deacetylation plays an important role in medicine and environmental protection. The functions of chitosan of antibacterial, preservation and packaging in the food industry and application in environmental protection and tissue engineering were introduced to provide reference for the determination of the deacetylation degree of chitosan.