The invention discloses a method for removing sulfur dioxide in smoke by using white mud, which uses the white mud plasma as desulfurization solution, and implements the two-stage absorption desulfurization to the sulfur dioxide in smoke and then dissipates fog and discharges the smoke. The desulfurization solution absorbed in the first stage is collected at a low position, and is stored for recycling thereby forming a low position cycle, and the desulfurization solution absorbed in the second stage is collected at a high position, and is stored for recycling thereby forming a high position cycle; the desulfurization solution stored in the high position cycle overflows to the low position cycle, and the desulfurization gypsum generated in the low position cycle is pumped out for cyclone separation, top-flowing thin gypsum plasma refluxes to the high position cycle, and the bottom thick gypsum plasma is treated for deslagging. The invention also discloses a device for realizing the method. The inventive method and device has reasonable design and can effectively improve desulfurization efficiency.