Biodiesel has been traditionally produced using batch reactor technology. However, for obtaining a large of product in batch process, large reactor size, high energy consumption and high labor cost were required. In addition, the quality of the product in each batch was difficult to control. In order to reduce the batch process problem; therefore, the continuous process was investigated. The continuous reactor can be classified into 3 types: continuous stirred tank reactors (CSTR), plug-flow tubular reactor (PFR), and packed bed reactor (PBR). A CSTR was chosen for producing biodiesel from high free acid MCPO via the two-stage process in this investigation because of low investment cost, suitability for liquid –liquid reaction and simply design.