Abstract: Taking a 50 MW class steam turbine with steam supplement for waste heat utilization as the research object, the measurement method of the steam dryness at inlet of the steam separator was proposed, and the pressure loss of main stop valve and control valve was analyzed. The correction coefficient of generator output power of this type of unit was given, while the unit performance was tested and verified according to ASME PTC6—2004 code. Test results show that the corrected generator output power is 53 115.9 kW, which is 1 605.9 kW more than the design value of 51 510.0 kW. It is proved that the unit performance can meet the design requirements.