In this study, we researched the optimal conversion conditions of biodiesel for the transesterification reaction of microalgae lipid in supercritical alcohols. To investigate the transesterification of microalgae lipid, the microalgae lipid to alcohol mol ratio was varied from 1:360 to 1:540 between the temperatures 210 and 350 ℃ at an interval of 15 ℃ in a 25mL batch reactor. Also, the experiment was performed at 15 minute interval between 0 and 60 minutes in the optimal temperature range. The products were analyzed by gas chromatography mass spectrometry. In order to know a more accurate conditions, the optimum reaction was designed response optimizer of using response surface method.