Abstract: A Cs-AA-HEMA complex hydrogel was synthesized in acrylic acid solution from chitosan-acrylic acid-hydroxyethyl methacrylate as raw materials,cerium ammonium nitrate,benzoyl peroxide as initiator and glutaraldehyde as crosslinker.The process and theory of hydrogel swelling were studied.The effects of various factors such as preparation conditions and solvent properties on the degree of equilibrium swelling were investigated.The results showed that the degree of equilibrium swelling ratio of complex hydrogel increased with increasing the concentration of acrylic acid and hydroxyethyl methacrylate first and then decreased afterwards.However,the degree of equilibrium swelling decreased with increasing concentration of glutaraldehyde.The complex hydrogel was pH/ion/temperature-sensitive.