Preparation method of chitosan hydrochloride

An embodiment of the invention relates to a preparation method of chitosan hydrochloride. The preparation method comprises the following steps: mixing water, ethanol and hydrochloric acid according to the mass ratio of 1.0-2.5:1.0-1.8:1 to obtain a reaction pre-mixed solution; cooling the reaction pre-mixed solution, and reducing the temperature of the reaction pre-mixed solution to be below 10 DEG C; adding chitosan in the cooled reaction pre-mixed solution to obtain a mixed material; feeding the mixed material in a channel mixer; after stirring uniformly, packing the mixed material in a double-layered inner-film bag, compacting and sealing a bag opening of the double-layered inner-film bag; placing the double-layered inner-film bag in an incubator and insulating; placing the insulated material in a cleaning tank, adding the ethanol of which the weight is 2.5-4.5 times greater than that of the chitosan, soaking and centrifuging; placing the centrifuged material in a vacuum drying box and drying; sieving the dried material by using a sieve with meshes of 20, and then pulverizing; and sieving the sieved material by using a sieve with meshes of 80 to obtain the chitosan hydrochloride.