Biodiesel has attracted considerable attention during the past decade as a biodegradable, nontoxic, and renewable fuel, Several processes for the production of biodiesel have been developed, among which transesterification under alkali-catalysis gives high level yield of methyl esters in short reaction times. In this research, response surface method was applied to optimize the transesterification reaction under alkali-catalysis. It was found that reaction temperature, reaction time, and agitation rate of reactor had profound effects among the seven variables affecting on biodiesel conversion. The optimal temperature, reaction time, and agitation speed were 67$^{circ}C$, 68 minutes, and 94 rpm, respectively. Under the optimal conditions, the experimental value of biodiesel conversion was 99.7%.