Abstract: For the sulfur recovery unit in a high sulfur purification plant, liquid sulfur corrosion coupon testing was performed to study the corrosion resistance of 20G, 16MnR, 304L and 316L steels in sulfur recovery unit, and corresponding preventive measures were put forward. The results show that 304L and 316L austenitic stainless steels had good corrosion resistance in liquid sulfur, while 20G and 16MnR steels suffered serious H2SO3/H2SO4 dew point corrosion, H2O-H2S corrosion and high-temperature sulfidation corrosion, and the corrosion mode was mainly uniform corrosion. The corrosion rate of 20G steel and 16MnR steel increased when the process temperature was very high or very low and when the water content and oxygen content increased. The corrosion products on 20G steel and 16Mn steel were mainly iron sulfide and oxide. In corrosive vapor, the corrosion products on 20G steel and 16MnR steel were mainly FeSO4 and FeSO3, in addition, a small amount of iron sulfide and oxide were found. Based on the results above, setting corrosion monitoring points and monitoring these points for a long time were suggested. What′s more, it is necessary to keep suitable repairing and maintenance for the easily corrosive positions.