Abstract: The D9 type pipe clamp of main steam pipe hanger in a power plant was deformed. The deformation causes of pipe clamp were analyzed by means of chemical composition analysis and finite element analysis. The results show that the maximum tensile stress of the clamp was 124 MPa, which was located on the outer surface of the bending angle of the clamp. The maximum tensile stress exceeded the allowable stress value of the material, which accelerated the creep rate of the pipe clamp at high temperature. The creep deformation accumulated continuously and made the deformation of both ends of the pipe clamp warping obviously.