Abstract: Crack analysis of SA-213TP347H steel pipe in high temperature reheater was carried out by means of structure analysis, fracture analysis, hardness measurement, tensile test, optical microscopy and EDS. The result shows that the high temperature reheater is easy to shake during operation. The cracks are located at the pits of the pipes caused by the squeezing of the pipe clamp. The tensile property and hardness meet the requirement of ASMEA213/A213M. The microstructure is made up of austenite and Cr carbide at the grain boundaries. The cracks propagated along the grain boundaries, from the outer surface to the inner surface of the pipe. The corrosion products of the cracks contain O and S non-metallic elements. It is concluded that because of the squeezing of the pipe clamp and the instability of the pipes, higher stress at the deformed area accelerated the precipitation of Cr carbide at the grain boundaries, resulting in the Cr-depleted zone, which caused intergranular stress corrosion under the corrosive medium.