In biodiesel production via transesterification, after removing glycerol from crude biodiesel, purification process must be performed before using biodiesel as a fuel that meets the EN 14214 standard. In the literature, various processes are presented for purification of biodiesel however; dry and wet washing methods are mostly recommended because of their higher efficiencies and easier applicabilities. In this study, methyl esters (biodiesel) derived from waste frying oil (WFO) and sunflower oil were generated using transesterification technique in the presence of KOH and methanol in a novel microwave assisted biodiesel reactor. For purification of crude biodiesel, two different methods; washing with distilled water as wet washing, and with magnesol as dry washing were carried out and compared. According to the results, dry washing method improved biodiesel yield and ester content, it also reduced the purification process time considerably