Abstract: Lipolase was chemically modified with fatty acids. The hydrolysis activity，interfacial hydrolysis activity and esterification activity in hexane of the modified lipolase were assayed. The results showed that the interfacial hydrolysis activity and esterification activity of the modified lipolase increased apparently，although the hydrolysis activity decreased a little compared with the unmodified lipolase. The surface tension and the interfacial tension of the modified and unmodified lipolase were also investigated. The surface tension and interfacial tension of the solution of modified lipolase were much lower than those of unmodified lipolase. The Langmuir-Blodgtt monolayer film of modified lipolase was obtained by the use of LB technique and the surface pressure was higher than that of unmodified one，showing that it was much easier to congregate on the interface. All results showed that lipolase modified with fatty acids had an enhanced activity on the interface，making it advantageous to use modified lipolase in organic solvent and two phase system.