The extracellular hemicellulase from Penicillium was immobilized on chitosan by glutaraldehyde.The results indicated that the immobilized-hemicellulase prepared by 0.5 g chitosan crosslinking with 4% glutaralhyde and then combining with 2.5 mg protein showed higher enzyme activity and better activity recoveries(45.6%).The optimum pH of soluble enzyme and immobilized enzyme were pH 4.6 and pH 3.6 respectively.The optimum temperature of soluble enzyme was 55℃, whereas immobilized showed high activity in 60～75℃.Thermal stability of immobilized enzyme was better than soluble enzyme at 65℃.The apparent K_m′ of the immobilized enzyme was 3.58×10^－2 g/L and the K_m of soluble enzyme was 5.0×10^－2 g/L with hemicellulose as the substrate.