Abstract: The products of transesterification reaction of tung oil are mainly eleostearic acid methyl esters which not only can be used as a kind of renewable energy-biodiesel, but also an important chemical material. Immobilized enzyme was used to catalyze the transesterification reaction of Tung seed oil and methanol in this article. NOVO435 lipase was catalyst, and the response Surface methodology was used to optimize the transesterification reaction conversion of tung oil in non-solvent systems. The optimized reaction condition was found: rotation rate is 200rpm、the molar ratio of methanol and oil is 2.2:1、reaction temperature is 43℃、the mass ratio of catalyst and oil is 14% (based on the weight of oil), and after reacting for 18h, about 67.5% of the oil conversed to its corresponding methyl esters (the academic conversion is 73.3%). The esters conversion of tung oil was decreased by 6% after the lipase being used for 120h, and the lipase was washed by organic solvents after each reaction. Theoretically the molar ratio of methanol and the oil is 3:1, but methanol cannot be inserted in one time, and if the methanol was inserted by two steps, and about 85% conversion was gotten after 36h of reaction