The present invention discloses an injectable in-situ crosslinkedhydrogel and its preparation method. The preparation method is as below:Filling the crosslinking active solution of at least one kind of thebiocompatible macromolecules containing more than two thiol groups onthe side chains into an injectable container and sealing it, and forming thein-situ disulfide-bond crosslinked hydrogel under the action of thedissolved oxygen； through controlling such parameters as partial pressureof oxygen gas, temperature and time, regulating concentration of theoxygen dissolved in the crosslinking active solution, and optimizing thegelation process and the gel properties. The present invention furtherrelates to application of the injectable in-situ crosslinked hydrogel inpharmaceutics or surgery. The present invention has many advantages,such as no need for a crosslinking agent, simple preparation process,convenient application, containing no impurities, good biocompatibility,no toxic and side effect, and wide application in the medical science.
