shows that ultrasonic power has a direct effect on the yield and methyl ester contents of the produced biodiesel. In the constant conditions of temperature, catalyst and MRs, reaction yield increases with increasing ultrasonic power. With increasing ultrasonic power from 100 to 400 W yield of reaction increases from 73% to 79.86%. Ultrasound mixing is the main parameter in 100 and 200 W power. It can be seen that when the mixing is not complete in 100 and 200 W the yield of reaction does not have significant change. In higher ultrasonic powers, energy density and cavitation activity have been increased. It causes better mixing in the reactor. The methyl ester content is decreased a little at 400 W which may be due to the experimental errors in GC measurement.