Combined with the advanced flue gas desulfurization(FGD) technology at home and abroad at present, the technical and economic comparisons and optimization proposals are implemented of seawater desulfurization plan for two 350 MW and two 50 MW units in the thermal power plant, including ensuring the safe and reliable operation of the plants, optimizing SWFGD(seawater FGD) system and general layout, saving the project investments and lowering operating costs, The preferred plan of SWFGD system for this kind of project is recommended.