The invention provides a priority management system of a nuclear power plant; the priority management system of the nuclear power plant is mainly used for managing instruction priorities and interfaces among a digital instrument control system and other systems of the nuclear power plant and driving devices of engineered safety facilities; the priority management system is used for directly receiving instructions from an engineered safety driving cabinet ESFAC, a safety related control cabinet SRC, a diversified driving control cabinet DAC, a serious accident control cabinet SAC and a power plant standard automatic system PSAS in a hard wiring manner, collecting feedback information of a field executor, supporting a self-diagnostic function and a periodic test of a safety system, and transmitting the feedback information, a self-diagnostic result, a quantitative test result and the like of the field executor to a DCS (Data Communication System) of the nuclear power plant; the priority logic part of the priority management system is in the form of a logic circuit; therefore, the priority management system is completely different from the DCS; and thus, software common-cause failures can be effectively avoided.