Lipase was lyophilized with cyclodextrins to prepare lipase formulation suitable for the efficient resolution of allethrolone in ionic liquids. The effects of the type and amount of cyclodextrin used on lipase preparation were evaluated, and the properties of lyophilized lipase such as thermostability and pH sensitivity were investigated and compared with those of native lipase. The results showed that lipase lyophilized with cyclodextrins can achieve a higher conversion rate than the native one, and that lipase lyophilized with inorganic salts cannot improve the conversion rate of the resolution reaction. The catalytic behavior of the lyophilized lipase was strongly dependent on cyclodextrin type and reaction media. The activity of the lyophilized lipase increased as the amount of added cyclodextrins increased. The activity of the lipase lyophilized with cyclodextrins was optimum at pH 7 and 40 degrees C, which was similar to that of the native one, but the half-life of the lyophilized lipase was low compared with that of the native one.