For pressurized water reactor nuclear power plants that mainly rely on active equipment to mitigate accidents, the availability of power sources is directly related to the effectiveness of accident mitigation. To mitigate and respond to design extension conditions such as a station blackout, power sources at different levels of defense in depth are mainly set up for protection. Equipment such as emergency diesel generator and additional diesel generator is an important part of them. In the current design, the power supply loading load sequence for power sources including diesel engines is a fixed sequence determined based on the analysis of expected assumed working conditions. This inflexible design will lead to the expected equipment loads not being loaded due to faults when the unit experiences superimposed faults of different equipment, the power supply capacity not being fully utilized as designed, and other important equipment for accident mitigation not being loaded as early as possible, which is not conducive to accident mitigation. Based on the design of a one-million-kilowatt nuclear power unit, this paper has developed a set of programs for dynamically planning the power supply load list based on the actual unit state to realize the real-time optimization of the power supply loading load list under different working conditions.