Abstract: In this paper, the adsorption characteristic and storage stability of Horseradish peroxidase immobilized on Fe 3O 4 were studied. The effects of enzyme concentration, pH and H 2O 2 concentration on the treatment of organic chloride catalyzed by immobilized enzyme were discussed in detail. The removal of chlorophenol by immobilized enzyme was compared with that of soluble enzyme, and the results indicated that organic chloride treatment by immobilized enzyme had great advantages.