The invention provides a preparation method of an injectable high-strength chitin-based hydrogel product. The preparation method comprises the following steps: preparing binary or polybasic alkynyl modified hydrophilic polymer A, preparing an amino-containing chitin derivative B, mixing an aqueous solutions of A and B to form an injectable hydrogel precursor solution, and forming high-strenght hydrogel in situ under the physiological condition. The injectable hydrogel is prepared in situ under the physiological condition by utilizing spontaneous amine-alkyne click reaction and performing chemical crosslinking by forming enamine bond, any micromolecular catalysts, initiators or crosslinking agents are not needed, heating, ultraviolet or radiation is not needed, no toxicity and no irritationare realized, and any aftertreatment is not needed. In-situ physical crosslinking rapid formation is conducted by using a temperature-sensitive chitin derivative, and in-situ crosslinking is furtherconducted to prepare the injectable high-strength hydrogel. The hydrogel has high biocompatibility, pH sensitivity and biodegradability, and can be widely applied to the field of biological medicine.