<p>This work focuses on evaluating the performance of a 660 MW ultra-supercritical power plant from the perspective of energy saving ability. By conducting the exergy analysis, the exergy loss distribution and the efficiency of regenerators are thoroughly measured. The results show that the exergy loss of a high-pressure regenerative heater can be as high as 3.03 MW. Thus, installing outer steam coolers can reduce the exergy loss of high-pressure regenerative heaters. The energy saving potential of different configurations across wide load conditions is further analyzed. These analyses reveal that the flue gas waste heat utilization configurations not only alter the exergy loss distribution in the regenerative heating system but also reduce the need for high-grade extraction steam, thereby enhancing the unit’s power generation capacity. Based on the proposed optimal configuration, the gas-water heaters with high-temperature and low-temperature heat sources are utilized to heat the corresponding feed water, enabling a cascade utilization of waste heat. This approach minimizes the standard coal consumption for power generation of the unit to 253.39 g·(kW·h)⁻¹, 1.27% lower than the reference unit. Under rated conditions, the power generation increases by 5.99 MW. Under 40% THA condition, this configuration exhibits significant energy-saving benefits with a 0.97% reduction in coal consumption rate. Furthermore, the study has delved into the impact of turbine degradation, which is found to adversely affect the thermal performance of the power unit. This revelation provides crucial insights into maintaining and optimizing the performance of the thermal system.</p>