Methyl 15-hydroxy-pentadecanate,which was made from malana oleifera chum oil, was an ideal material to synthesize cyclopentadecanolide-an important macrocycle musk with wide applications in fields of perfume, cosmetic, food, medical and etc..One kind of screened lipase from Candida sp.GXU08 strain was used to catalyze the synthesis of cyclopentadecanolide from methyl 15-hydroxy-pentadecanate. Traditionally, the catalytic reaction went on under organic system, while an ultrasonic technology was innovatively used in water/organic biphasic system to systhesize cyclopentadecanolide and received good catalytic effect. Both organic and biphasic systems had the same optimal conditions as: substrate concentration 8 mmol/L, T=40 °C, ω=180 r/min,pH=6.0-6.5,and using lipase and reaction system twice would greatly increase the production of cyclopentadecanolide. It showed that the maximum production of cyclopentadecanolide was 47.77×10-3mg/U in biphasic system under the optimal conditions,which was 3.285 times of that in organic system. It would save the process of freeze drying and improve the production of cyclopentadecanolide. It verified that methyl 15-hydroxy-pentadecanate would directly cyclize into cyclopentadecanolide in organic system. While in biphasic system,it would hydrolysis into 15-hydroxypentadecanoic acid firstly, and then cyclized into cyclopentadecanolide.