Chitosan was obtained from crab shells by treating with HCl and NaOH. The conditions of cellulase immobilized on chitosan by glutaraldehyde were studied. The results indicated that the immobilized-cellulase prepared by 0.1g dry chitosan cross-linking with 5% glutaraldhyde and then combining with 4.0 mg cellulase showed higher cellulase activity and better activity recoveries (75% ). And some characters of immobilized and native cellulases, such as optimum temperature Michaelis constant and the effect of ionic strength, stabilities to heat and repeat operation were studied and compared.