The invention belongs to the technical field of wet method desulfurization technology tail gas dewatering postprocessing, and provides a rear spiral-separation dewatering device for smoke water removal. A water removal pipeline is added on the basis of a smoke water removal device, after smoke enters a smoke inlet to be sequentially dewatered and processed by a spiral-separation blade and the water removal pipeline, gas is discharged out of a smoke outlet, and a water body is discharged out of a drain outlet in the lower portion of the water removal pipeline. In actual work, after the water-containing smoke enters the water removal pipeline through a gas inlet pipeline under the flow guide effect of the spiral-separation device and inverted circular truncated cone-shaped filler, the smokehits wall surface drainage filler, and under the effect of a high-molecular drainage material, liquid drops condense and converge and then flow out of a smoke duct so that the final smoke dewatering aim is achieved.