A novel degradable pH-sensitive hydrogel with pendent carboxyl groups was designed and synthesized from ethylenediami- netetraacetic dianhydride (EDTAh) and butanediamine (BDA) with dicyclohexylcarbodiimide (DCC) as a condensating agent and BDA as a crosslinking agent.The obtained polymers were characterized by ~(13)C NMR,~1H NMR and FTIR.The swelling experiments of the hydrogel in pH 3,7,and 12 media indicated much higher swelling ratio in pH 12 media than in pH 3 and pH 7 media,exhibiting sound pH sensitivity.The pH sensitivity of this type of hydrogel may be regulated through controlling the type and the dose of the crosslinking agent. A novel degradable pH-sensitive hydrogel with pendent carboxyl groups was designed and synthesized from ethylenediami- netetraacetic dianhydride (EDTAh) and butanediamine (BDA) with dicyclohexylcarbodiimide (DCC) as a condensating agent and BDA as a crosslinking agent. ~ (13) C NMR, ~ 1H NMR and FTIR. The swelling experiments of the hydrogel in pH 3, 7 and 12 media indicated much higher swelling ratio in pH 12 media than in pH 3 and pH 7 media, exhibiting sound pH sensitivity The pH sensitivity of this type of hydrogel may be regulated by controlling the type and the dose of the crosslinking agent.