When the CONSOLV tail gas treatment unit is applied to treat high-temperature sulfur-containing flue gas in a natural gas purification plant, an annular corrosion ring has been observed about 30 cm above the spray water line of Venturi section of the combined Venturi quench tower. This study addresses the issue of equipment corrosion. Using computational fluid dynamics software the fluid dynamics, heat transfer, and mass transfer processes within the Venturi is simulated and analyzed. The corrosion mechanism is investigated, and optimization solutions are proposed. The cause of the corrosion is attributed to the formation of sulfuric acid when the high-temperature sulfur-containing gas comes into contact with water vapour during the cooling process. When the gas temperature drops below the sulfuric acid dew-point, high-concentration sulfuric acid droplets form, leading to severe acid corrosion on the inner wall of the 254SMo high alloy stainless steel equipment. According to the corrosion mechanism, the internal corrosion of Venturi segment cannot be completely resolved. An improvement strategy for corrosion mitigation involves changing the spray atomization effect or the spray angle of the nozzle. The research results can provide valuable reference for the design, operation and maintenance of similar quench towers with Venturi section.