Abstract: SiO₂/alginate gel composites derived from 3-aminopropyltrimethoxysilane and sodium alginate were prepared through covalent cross-linking reaction. The gel biocomposites were used as carriers for the immobilization of cellulase. The loading efficiency (%) of the immobilized cellulase exceeds 86%,  and the SEM photographs show that the cellulase is distributed  homogeneously  in the carriers. The activities of the free cellulase and immobilized cellulase were determined by measuring the amount of the glucose made from carboxymethyl cellulase under the given conditions. The results show that the immobilized cellulase has a higher Michaelis constant( K_m) than free cellulase. The immobilized cellulase has better stability with respect to pH and temperature than the free cellulose. The optimal pH  of enzyme is 3.6 and the optimal temperature of enzyme is 50℃.The storage and recycling stability of the cellulase increase after immobilization, it also remains up to 50% relative activity after 10 cycles and remains 81% relative activity after being stored for 30 days.