Abstract: The Wet Flue Gas Desulfurization (WFGD) is widely used in flue gas purification, which always leads to numerous white mist causing adverse public effect and dew point corrosion of the stack. Based on the reasons analysis of forming white mist, the impact of water content and gas/gas heater (GGH) was analyzed for the sulfur recovery unit of a refinery. The results showed as follows: (1) the 1% increase of water volume fraction led to about 1.13 ℃ rise of the flue gas dew point, the 1 ℃ decrease of cooling feed gas resulted in the 0.925 ℃ increase of exhaust temperature and the decrease of 690 kg/h water consuming; (2)after comprehensively considering the equipment investment and heat transfer effect of flue gas, it was suitable to control the cooling feed gas temperature at 150-180 ℃; (3) when the free water content was controlled at 0.01 wt% by the highly efficient mist eliminator and feed gas was cooled to 165 ℃ by GGH, the water content in discharged flue was decreased by 6.21 vol%, the flow of make-up water was decreased by 690 kg/h, the flue discharge temperature was raised by 122 ℃. After taking above measures, the white mist and the water consumption was reduced simultaneously.