Abstract: When the main steam inlet pipe of supercritical 600 MW steam turbine operates in a long term in the supercritical conditions,the unit is designed to overlay Stellite alloy on the intubation surface to increase the resistance to erosion and shock resistance,so as to ensure the safe operation of the unit.In this paper,the cracking causes of Stellite alloy in the main steam high pressure inlet pipe of a supercritical steam turbine are analyzed.The repairing technique of Stellite alloy crack is proposed after the simulation experiment and field practice,which can provide reference for the repair of Stellite alloy crack in the same type of unit.