Abstract: The failure analysis was carried out on the dissilient 12Cr1MoV steam pipe which was worked in the high-temperature 514 ℃ and atmospheric pressure 15.6 MPa.The results show that pearlite spheroidization and carbide precipitation on the grain boundary near the fracture leaded to a great number of crack coming from creep hole in certain areas were the main reasons of the pipe failure.The working parameters should be strictly controlled in order to avoid excessive atmospheric pressure and the steam pipes should be periodic detected.