Abstract: The cold and hot state indications of all constant hangers of the drum decentralized downcomer in a power plant indicated upward stuck, and the vertical thermal expansion of the pipe was seriously blocked. By means of load test and finite element simulation, the failure causes of the constant hanger of the decentralized downcomer were analyzed. The results show that the reason for the failure of the constant force hanger of the decentralized downcomer was that the constant hanger was too large, which caused the maximum stress of the pipeline to increased by about 9%, and the thrust moment of the port was significantly increased, but the stress in the port area was still within the safe range, which could meet the needs of safe operation.