A comprehensive investigation of flue gas desulfurization was carried out by hydrophobic polypropylene hollow fiber membrane contactor with seawater as absorbent. The effect of various factors, such as membrane packing density, flow path of gas and fluid, concentration of SO2, gas temperature, configuration and connecting form of membrane contactors on desulfurization efficiency were studied. It is beneficial to absorption efficiency of SO2, with the increase of flue gas temperature, seawater flux, the contacting area between gas and seawater, stage numbers of membrane contactors, as well as the distribution degree of uniformity of gas and liquid in the membrane contactor. The absorption process could be enhanced when the flue gas was fed into the lumen side of the membrane module, whereas the gas pressure was too high for the pracrtical utilization. The module configuration plays an important role in improving the mass transferring. The development of new module of membrane contactor and membrane structure/materials for improving mass transferring would be fundamental factor to increase the absorption efficiency.