Abstract: Under the new situation of normalized participation in deep peak regulation, low load, and flexible operation, some supercritical and ultra-supercritical boilers encounter the common problem of transverse cracks in the water-cooled wall during actual operation. The boiler is particularly prominent, which seriously affects the safe and stable operation of the unit. Combined with the field case of the wall-type tangentially fired boiler, this paper analyzes the occurrence characteristics of the transverse crack of the water wall, and summarizes the main reasons for the transverse crack of the water wall combined with the literature. Finally, the countermeasures to the problem of transverse cracks in the water wall are discussed in a targeted manner.