Abstract: The cracking part of acidic water stripping tower in hydrogen production unit of a refining enterprise was systematically analyzed by macro/micro morphology, stress condition, material chemical composition, metallographic structure and fracture characteristics. At the same time, the working conditions inside the stripping tower, the composition of the medium, the types of external insulation materials and the content of pollutants were combined to the above. The results showed that the cracking of stripping tower was due to the water retention in the outer wall insulation, which led to a continuous concentration of soluble chloride in the insulation material on the surface of S30408 stainless steel. Meanwhile, the stainless steel suffered chloride stress corrosion cracking from the outside of the tower. It is suggested to optimize the insulation structure design and insulation material selection, strengthen construction management of insulation structure, and apply anti-corrosion coating to avoid the corrosion and cracking.