Magnetic Fe3O4/chitosan nanoparticles were synthesized for lysozyme separation from solution. The adsorption of lysozyme was investigated on magnetic Fe3O4/chitosan nanoparticles at fixed pH 6.0, because the enzymatic activity of lysozyme reaches its maximum in this condition. The influence of initial lysozyme concentration, temperature and contact time on lysozyme adsorption was studied. The results of lysozyme adsorption indicated that the adsorption isotherm fitted Sips model well. The maximum adsorption capacity was 144.11mg/g at 310 K. The thermodynamic parameters, ΔG0, ΔH0 and ΔS0, illustrated that the adsorption of lysozyme was endothermic and spontaneous process.