Abstract: The protection of immobilized cellulase by trehalose during drying and storage is investigated. It is found that trehalose can reduce the activity losts of immobilized cellulase efficiently during its drying, and the mass ratio of trehalose and enzyme is about 0.25 at 58 ℃. The stability of immobilized cellulase increases with increase of trehalose or decrease of storage temperature. By mean of infrared spectrometry and DSC, the mechanismof protection of immobilized cellulase by trehalose is studied. Increase of stability of immobilized enzymes is not only because of the interaction between trehalose and enzyme, but also because of the formation of a glassy state in and around enzyme moleculars, especially near active sites of enzymes, so that the structure of enzymes is restricted, and activities of enzyme can be preserved at a high temperature.