In the daily energy-saving statistics of coal-fired power stations, the imbalance of the total standard coal consumption often occurs. The fundamental reason is that the boundary conditions of the steam turbine side heat rate calculation and the boiler efficiency calculation are not unified. The article first analyzes the existing calculation methods, and points out that the anti-equilibrium calculation of boiler thermal efficiency lies in various loss calculations, and the key to the calculation of steam turbine heat consumption rate lies in the calculation of heat absorption. The heat consumption rate of the steam turbine is based on the flow into the turbine. The loss of working fluid on the turbine side, such as oxygen exhaust, high-pressure operation exhaust, sampling, valve leakage, etc., have been taken into account. Sampling, heat tracing in the ammonia station, and leakage from the boiler side run-off do not affect the boiler efficiency, nor the calculation of the turbine heat consumption rate, but affect the overall operation level of the unit. This article researchs the calculation method of coal consumption for power supply,taking a 600MW condensing power plant as an example, the main reasons for the difference in calculation results are analyzed, which lays the foundation for energy-saving diagnosis and energy-saving potential of the whole plant.