Abstract: Steam leakage accidents occurred in the front wall reheater tube, water wall tube and partition screen tube of a power plant boiler. The causes of boiler tube cracking were analyzed by means of macroscopic observation, metallographic examination and hardness test. The results show that the cracking point of the boiler tube was located on the wall reheater tube. The cracking reason was not the overheating of the tube or its own defects, but the wrong welding between the sliding plate and the front side of the 31 wall reheater tubes near the furnace during the installation and construction process, resulting in defects and cracking of the tube.