The invention discloses a preparation method of degradable in-situ gel. The preparation method comprises the following steps of preparing sulfhydrylated chitosan (CS-SH) and alkynylated polyethylene glycol (Alkynyl-PEG) from the main raw materials including natural macromolecule chitosan and polyethylene glycol; and dissolving and mixing sulfhydrylated chitosan and alkynylated polyethylene glycol with collagen in different proportions, so as to rapidly form the in-situ gel through click reaction. The gel is prepared in a click chemical manner and has good stability; by taking natural macromolecules with good biocompatibility as the main raw material, the gel has good degradability; the gel can load medicines, and a gel network is formed, so that the control and release of the medicine molecules are promoted; the gel contains collagen and is capable of promoting blood coagulation; and the gel is capable of simulating environments of extracellular matrix polysaccharides and proteins and can be used as a 3D stent material for culturing tissue engineering cells.