Abstract: In order to solve the problem of internal slurry circulation and water balance of the double-tower double-cycle wet-FGD system in the limestone-gypsum desulfurization process,a simple slurrycirculation mode between the two towers was proposed and applied in a flue gas desulfurization systemof a 2×350 MW unit in Shanxi. The results showed that the design desulfurization efficiencies of thefirst-stage tower and the second-stage tower were 87% and 97%,respectively. The design was simpli-fied while the replacement of spare parts was improved. The slurry circulation between two towers wasestablished by liquid level difference design and forced circulation pump. The slurry of the first-stagetower was diverted to the second-stage tower through the slurry circulation system,and the excess slurryof the second-stage tower overflowed back to the first-stage tower to build a water balance system be-tween the two towers. Under the working conditions of 187 MW or 290 MW,4-layer spraying couldreach 99.81% desulfurization efficiency after the slurry circulation system was started. Compared withindependent operation mode of two towers in the double towers system,the new double - towercirculation mode could guarantee the desulfurization efficiency by starting 6 circulating pumps,and re-duce the system resistance by about 500 Pa and the fan power consumption by 400 kW. Close-