To improve the full load economy of a 1 000 MW ultra-supercritical unit, the opening point of its overload valve was reduced to 850-950 MW. Simultaneously, a No.0 high-pressure heater and a bypass regulating system for the high-pressure heater were added on the basis of its original regenerative system. The No.0 high-pressure heater would be put into operation at low load, whereas the overload valve and the high-pressure heater bypass system would be put into use at high load. Moreover, the steam parameters and unit economy were compared before and after optimization, while the generating capacity was demonstrated, and the overall economy of various schemes was compared at different load rates. Results show that the main steam pressure increases and the heat rate reduces under part-load conditions after optimization of the unit. The economy of unit could be further improved by putting No.0 high-pressure heater into operation. The generating capacity could be increased by running the overload valve and the high-pressure heater bypass system, thus to satisfy the requirements of rated and maximum power output of unit. The overall economy of unit is greatly influenced by the load rate, which therefore should be considered in the selection of optimization schemes.