Aminoethyl chitins (AEC) with different amino contents were synthesized from chitin and 2-chlorethylamine hydrochloride, and the AEC hydrogels were prepared by crosslinking with glutaraldehyde. The microstructures, swelling behaviors and antibacterial activities of the hydrogels were investigated. The results of Fourier transform infrared spectroscopy (FTIR), (1)H nuclear magnetic resonance ((1)H NMR) spectrum and scanning electron microscopy (SEM) showed that the hydrogels were prepared by forming the Schiff base from AEC and glutaraldehyde. The aminoethyl chitin hydrogels were sensitive to acidic environment. The swelling ratio changed with the amino content of AEC, declined with the increase of the crosslinking agent concentration and increased with the increase of the AEC concentration. In addition, the antibacterial results of the hydrogels against Staphylococcus aureus (S. aureus) indicated that the hydrogels had good antibacterial activities, and the antibacterial properties were affected by the amino content of AEC and the crosslinking agent concentration.