A single-drop extraction apparatus was used to investigate the dependency of mass transfer coefficient on the amount of surfactant added. The mass transfer rate during drop formation and falling period, as well as the overall mass transfer coefficient were studied. The theory of dynamic surface effect was used to explain these phenomena. The results show that the mass transfer resistance increases with the added amount of SLS when the surfactant concentration is below 20 ppm. If the concentration is higher than this value, the resistance becomes constant. The mass transfer during drop formation plays an important part on the overall mass transfer efficiency and will be significantly affected by the presence of surfactant. According to this study, it is more appropriate to explain the mass transfer resistance induced by the surfactant from the viewpoint of hydrodynamics, rather than from the model of barrier layer.