The invention relates to chitosan double-network quick response-type injectable hydrogel and a preparation method thereof. The injectable hydrogel is prepared from chitosan or derivatives of the chitosan and sodium glycerophosphate serving as raw materials, and dialdehyde compounds or diepoxy compounds serving as crosslinking agents, wherein the mass ratio of the chitosan to the sodium glycerophosphate is 1:(0.5-10); the mass ratio of the crosslinking agents to the chitosan is (0.01-1):1. The method comprises the following steps: evenly mixing a hydrochloric acid aqueous solution of the chitosan with a sodium glycerophosphate solution in the environment at -1 to 5 DEG C, so as to obtain a solution of which the pH is 7-7.2, and evenly mixing the solution with a crosslinking solution at 35-37 DEG C. Transformation from a sol state to a gel state can be quickly finished under a specific condition, the process is irreversible, and the transition time is controllable. The chitosan double-network quick response-type injectable hydrogel has the advantages of simple reaction condition, short response time, good thermal stability of gel, high mechanical strength, good biocompatibility and the like. The chitosan double-network quick response-type injectable hydrogel is applied to the fields such as tissue filling and repairing, biological scaffolds, scar resistance and anti-adhesion, biogel, and quickly molding or three-dimensional printing materials and the like.