Abstract: The corrosion failure cause of reboiler tubes of a desulfurization regeneration tower in a refinery was investigated by microscopy, XRD, SEM and EDS. The results show that there existed a number of cellular corrosion pits at the surface of puncture site of the reboiler tubes, consisting of a lot of S, Cl and other corrosion elements. The corrosion products were mainly composed of FeS₂ and FeS. The corrosion failure of the reboiler tubes was mainly caused by corrosion of the RNH₂-H₂S-Cl^--Thermal stable salts-H₂O system made up of the acidic materials of H₂S, CO₂ and Cl^- in raw material, and bubble corrosion. Finally, some measures and suggestions were put forward according to the failure cause.