Silk sericin protein powder can be produced from the sericin solution by the processing of degumming in the high temperature and high-pressure conditions, purifying, condensing and spray drying. Molecular mass of the sericin protein is high up to 200 ku. Taking on white color and about 10 μm average granularity, the powder of the protein is hot water soluble. L-Asparaginase was immobilized on the natural silk sericin powder by cross-linked with glutaraldehyde. The enzyme activity and dynamical properties of the immobilized L-asparaginase were described. It was found that the immobilized enzyme is very stable, and the stability to heat increased in comparison with free enzyme, and this immobilized enzyme has preferable stability of operation. The resistance to trypsin hydrolysis was also improved greatly compared to that of soluble enzyme.