Abstract: Taking the corrosion of the first stage condensate cooler at the outlet of the acid gas combustion furnace in a 40 000 t/a sulfur refining company as an example, the corrosion cause was evaluated through a series of methods such as preliminary leak test, observation of the morphology of the corrosion thinning perforation area, analysis of the chemical composition of corrosion products, and numerical simulation of the flow rate of the medium. The results indicate that the main reason for the corrosion perforation of the sulfur condenser tube bundle was the oxygen corrosion and alkali corrosion caused by the shell side medium not being deoxidized in advance and improper pH control. Based on the analysis results, corresponding anti-corrosion measures were proposed.