Two kinds of polymerizable vinyl quaternary ammonium salt, namely dimethyldiallyl ammonium chloride and trimethyldiallyl ammonium chloride respectively, were prepared via the SN ₂ nucleophilic substitution of the allyl chloride with the tertiary amine. The structure of the prepared quaternary ammonium salts were characterized through the methods of element analysis, FTIR, H ¹－NMR and C ¹³－NMR. Two kinds of polyampholytic superabsorbent polymer, which include CMCTS-g-(PAA-co-PDMDAAC) and CMCTS-g-(PAA-co-TMAAC) respectively, were prepared through graft copolymerization of prepared vinyl quaternary ammonium salt and acrylic acid onto the chain of carboxymethyl chitosan, initiated with persulfate and crosslinked properly. The structure of the superbasorbent polymer was characterized by FTIR. Influence of the pH value of the solution on the swelling ratio of the polyampholytic superabsorbent polymer was studied.