Abstract:A subcritical 600MW unit has higher heat consumption after the long-term commercial operation and its some monitoring parameters also deviate from the design ones besides for medium and low pressure cylinders efficiency and the extraction temperature of the fifth and sixth extraction steam, which reduces the unit economy. In order to meet the national energy conservation and emission reduction goals, the unit has been retrofitted with the micro-rise parameter flow path transformation. By using the advanced F3D technology, turbine’s flow passage structure was optimized and the turbine’s flow path passage was rebuilt. Through the optimization of unit parameters and structure, the unit"s various performance indicators have been significantly improved after the transformation, and the steam turbine heat consumption has been reduced by 328 kJ/(kW. h) under its assessment conditions, which has achieved good results, which can provide reference for the same type units.