In order to reduce the coal consumption and carbon emission of 600 ℃ double reheat ultra-supercritical (USC) coal-fired power generation system, an optimized system (scheme 2) for coupling tower solar energy to heat regenerative system feed water out of deaerator was proposed and compared on the basis of a 1 000 MW typical double reheat USC unit (scheme 1). The unit consumption analysis method based on exergy analysis is used to compare the thermal performance of different schemes of 1 000 level MW 600 ℃ double reheat unit and the energy consumption distribution of each scheme under variable working conditions was analyzed. The results show that the integration of solar energy heat into 600 ℃ double reheat USC coal-fired units can effectively reduce the coal consumption and carbon emission of unit. The standard power generation coal consumption rates of scheme 2 are lower than that of scheme 1 under variable conditions. Under 100% THA working condition, when 10%, 30%, 50%, 70% and 100% of the feeding water supply out of the deaerator are heated by solar energy, the standard power generation coal consumption rates of scheme 2 are reduced by 4.59、15.70、24.96、32.56 and 41.32 g/kWh, and the carbon emission are reduced by 12.70、43.50、69.10、90.28、114.50 g/kWh, respectively, so the effect of coal saving and carbon reduction is obvious. The unit consumption analysis method is used to study the additional unit consumption of each equipment unit of the unit. The additional unit consumptions of boiler, regenerative heater and condenser in scheme 2 are lower than that in scheme 1. The additional unit consumption of the boiler in scheme 2 is obviously reduced with the increase of the proportion of tower solarheating, while the additional unit consumption of tower solar energy is increased in scheme 2. Integration with solar energy can further improve the performance of coal-fired power plant.