The invention discloses a preparation method and applications of 
carboxylation chitosan. The preparation method comprises following steps: a dimethylsulfoxide solution of 
glutaric anhydride is delivered into a sealed reactor, and is heated, 
chitosan is added for reaction, an obtained product is reacted in 
sodium hydroxide solution so as to obtain 
carboxylation chitosan; 
carboxylation chitosan is dissolved in a 
solid acid solution, 
calcium chloride is added for dissolving, an obtained mixture is subjected to 
spray drying so as to obtain carboxylation chitosan hemostatic particles; carboxylation chitosan is dissolved in the 
solid acid solution, 
calcium chloride is added for dissolving, the obtained mixture is subjected to 
freeze drying so as to obtain carboxylation chitosan hemostatic 
sponge; carboxylation chitosan is dissolved in an acid solution, an obtained 
mixed solution is injected into a mould, the mould is sealedly coated with a one-way permeable membrane, and is immersed in an alkaline medium so as to obtain chitosan gel, the obtained chitosan gel is washed with deionized water until pH value reaches 7, and is immersed in a 
calcium chloride solution for crosslinking, an obtained product is collected, washed, immersed in a glycerine solution, collected, and drained, is added into absolute ethyl 
alcohol for single-surface 
steaming, and is dried so as to obtain carboxylation chitosan hemostatic membranes.