N-carboxyethyl chitosan (ACS) was formed by a Micheal reaction. Through the analysis of IR and 1H-NMR spectra, the Micheal reaction was carried out between - NH2 of chitosan and - C = C - of acrylic acid. ACS hydrogel (ACSG) was prepared by cross-linking with glutaraldehyde. ACSG show pH-sensitive swelling behavior, and the smallest swelling rate (SR) of ACSG is in pH5.0 buffer solution.With dosage of glutaraldehyde increasing, the SR of ACSG decreased. With grafting degree (GD) increasing, the SR of ACSG increased first and decreased afterward. Using bovine serum albumin (BSA) as a model medicine, the releasing behaviors of ACSG were investigated in vitro. In simulated gastric and intestinal fluid, the ACSG loading BSA (GD=20.45%) has better releasing behaviors.