Aiming at the wear and tear of swirler blades in waste incineration semi-dry flue gas desulphurization tower,numerical simulation was conducted by computational fluid dynamics (CFD) technique. The flow field of desulfurization tower without wear of swirler blades was analyzed. The influence of wear loss of upper swirl blades,lower swirl blades and lower inclined blades on the flow field of desulfurization tower were studied respectively. The results showed that the wear loss of upper swirl blades and lower swirl blades had little effect on the flow field of desulfurization tower. The wear loss of lower inclined blade causes the overall upward movement of droplets trajectory, enlarge the evaporation area inside the desulfurization tower, and reduce the overall pressure loss of the desulfurization tower.