Abstract: Corrosion is more likely to happen in the chimney when thermal power plants are equipped with the wet limestone-gypsum FGD system but without the GGH system. Taking the 150-m super-high reinforced concrete chimney in a power plant for an example, the inspection and analysis of the chimney and flue surfaces, the concrete strength, the corrosion depth and the corrosion products are launched. The results show that the flue corrosion is more serious than the chimney corrosion, and most of the corrosion products are sulfates. In addition, it finds that the higher the chimney, the heavier the corrosion degree of the tube and the corrosion degree is distinctly different along the toroidal direction. The cause analysis concludes that preventing the neutralization reaction, improving the quality of chimney design and construction and strengthening the inspection and maintenance during operation are effective measures to prevent or alleviate the chimney corrosion.