Today, the consumption of fossil fuels is known to be unsustainable due to the rapid destruction of valuable resources and the production of environmental pollutants, and it has prompted researchers to find a good alternative to this by using renewable energies and expanding them with the help of appropriate processes. Biodiesel is one of the best-suggested sources. Oscillatory baffled reactors with high stirring intensity in less time and more volume has attracted the attention of many researchers in recent years. This study aims to evaluate the two-chamber oscillatory baffled reactor in the continuous production of biodiesel. The ultrasonic system has been used as a suitable pre-mixer, and waste oil has been used to reduce production costs. The molar ratio of methanol to oil (1:6, 1:9, and 1:12), time (1, 3, and 5 minutes), oscillation frequency (2.4, 3.7, and 4.9 Hz), and temperature (40, 50 and 60 °C) are the four factors that were investigated in this research. The physical and chemical characteristics of the biodiesel produced follow ASTM standard D6751. The response surface method was used to optimize the content of methyl ester produced, and The results indicated that the highest performance of biodiesel is 95.28%, along with the lowest energy consumption of 58.80 in the molar ratio of 8.01, time of 2.55 minutes, oscillation frequency of 3.64 Hz and temperature 49.05 degrees Celsius. The production of biodiesel with a high conversion percentage and in a larger volume by the fluctuating flow reactor, which was associated with a shorter reaction time, was another result of this research.