The effect of operating parameters on the extraction and separation of La and Ce, from chloride solution containing one complexing agent lactic acid, using 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (EHEHPA, P507) as an extractant, has been studied. Results show that extraction efficiencies increase as pH and residence time increase, while decrease with the increasing of channel width and mixture velocity. A better separation effect is obtained using microfluidic extraction at optimal conditions. The extraction rates (0.1214 s(-1) for La and 0.3231 s(-1) for Ce) determined in microfluidic extraction, are much larger than those (0.0058 s(-1) for La and 0.0068 s(-1) for Ce) in conventional solvent extractors, which are largely attributed to the higher surface-to-volume ratio achieved in microfluidic experiments. The overall mass transfer coefficients (K(L)a) increase with increase in mixture velocity, while decrease with increase in channel size including channel width and length. The significant difference in K(L)a of Ce (0.05-0.162 s(-1)) as compared to La (0.004-0.129 s(-1)) imply better separation effect. Compared with conventional extractors such as mixer-settler and centrifugal extractor, microfluidic extraction has much higher mass transfer rates.