Abstract: The method was established and optimized of extracting lysozyme from egg white using the novel ionic liquidC₄MIM₃CB which was obtained by modifyingC₄MIMCl with Cibacron Blue F-3GA,the binding energy betweenC₄MIM₃CB and protein was analyzed by AutoDock Vina to study the binding ability of lysozyme toC₄MIM₃CB. Lysozyme products were obtained by affinity extraction and reverse extraction,desalination,concentration and freeze-drying. Results showed that,by studying of the influenced factor,the best extraction and separation conditions for above process were concluded as followed:the optimum pH for egg white powder solution was 7.0 and theC₄MIM₃CB containing ionic liquid was at a concentration of 8 mg/mL,the shaking time was 15 min and conditions for back-extracted KCl solution was 1.5 mol/L with pH7.0. Finally,12.3 mg lysozyme with 97.56% purity and 35000 U/mg activity could be obtained by 250 mg egg white power. The purified multiple was 37.39 and the enzyme recovery rate was 89.74%. The method had the advantages of high selectivity,simple operation,high purity and high activity.