Method for preparing chitosan in situ gel agent

The invention discloses a preparation method of chitosan in situ gel preparation, which belongs to the medicine technical field. The invention comprises the steps as follows: first, dissolving chitosan into water solution and /or water solution with cosolvent; second, adding medicine into the chitosan solution and stirring sufficiently; third, adding strong base-weak acid salt into the chitosan solution slowly in CO2 atmosphere and under the stirring condition, and keeping stirring; fourth, distributing the evenly mixed chitosan collosol into sterile bottles with stoppers for sealing or filling chitosan collosol into an atomizing device under the protection by CO2 and then obtaining the chitosan in situ gel preparation. The invention not only avoids using organic solvent in the cause of preparation production but also simplifies the preparation production flow and widens the preparation application ways.