Abstract: Claus furnace is an important equipment in desulfurization process. The structure of Claus furnace has a significant effect on the gas flow and reaction in the furnace. The choke structure, conventional process and acid gas supplemental process with different checker wall structure were numerically simulated, and the residence time and mixing degree of these structures were compared to find the optimal furnace structure. It was found that the checker wall structure significantly increased the mixing degree and residence time of the gas in the furnace. For different checker wall structures, the Claus furnace with the orifice plate extension and the double rotation checker wall structure had the best gas mixing effect and the residence time increased by 6.32 s compared with the choke structure. The acid gas replenishment process could reduce the mass fraction of SO2 and increase the yield of sulfur. It is beneficial to complete reaction in the Claus furnace to customize the flow field of the Claus furnace by selecting the optimal Claus furnace structure.