Abstract: The uniformity of slurry spray in the desulfurization tower has an important influence on the distribution of flue gas and the desulfurization reaction. It is of great significance to study the velocity inhomogeneity of flow field and structure optimization in the desulfurization tower to improve the desulfurization efficiency. Therefore, the quantitative analysis index unevenness was put forward. The relationship between unit load and desulfurization efficiency was established. The inner structure of the tower was optimized. Numerical analysis was used to analyze the variation trend of heterogeneity with desulfurization efficiency. The internal flow field of desulfurization tower with inlet velocity of 3.0,3.4,3.7 and 4.0 m/s was studied. Inlet guide vanes were added and flow field optimization was carried out by using inclined grid flow homogenizing plate. The velocity distributions of horizontal and vertical sections at different heights in the tower were analyzed, and the dynamic pressure changes along the vertical direction were compared. The results show that the load and desulfurization efficiency shows a significant negative correlation in the fluctuation, and the variation tends of desulfurization efficiency and velocity unevenness are basically the same, under all working conditions. The velocity unevenness ω in the middle area decreases by 10%,the dynamic pressure difference of the main desulfurization reaction area decreases by about 70%,and the outlet velocity increases by 0.1-0.2 m/s. The optimization structure could improve the velocity distributions inside the FGD tower, increasing desulfurization efficiency and flow uniformity. Also, it could reduce the possibility of slurry being wrapped out of the tower and help reduce the flow resistance and running cost.