${alpha}-amylase$ was immobilized on the surface of polyethylene glycol(M.W. 2000) grafted polyurethane film using diisocyanate in an attemp to develop enzyme immobilized polymeric materials. The surface morphology of the modified polyurethane film was examined by SEM. Effects of pH and temperature on the activity of the immobilized ${alpha}-amylase$ were investigated. The optimal pH range of the activity was $7.0{sim}7.5.$ The immobilized ${alpha}-amylase$ demonstrated high thermal stability and maintained consistent activity during long-term storage.