The chitin gel affinity adsorption medium with the magnetic response was prepared by embedding method, and its apparent structure and adsorption characteristic were determined. The results showed that the powder of Fe3O4 in the medium could non-specifically adsorb non-target protein which could be overcome by being washed thoroughly in NH4Ac containing sodium-phosphate buffer,and lysozyme could be isolated directly from washing solution of eggshell. It suggested that the affinity adsorption medium could be separated quickly in added magnetic field from the solid-particles such as pieces of eggshell and sands, which greatly simplified the procedure of lysozyme purification. The purified lysozyme showed a single protein band in SDS-PAGE ,the recovery rate of its total activity was 26%, and the specific activity reached 50894 U/mg.