The invention relates to a display device of a post-accident monitoring system in an advanced control room of a nuclear power plant, which is arranged on a back-up disk of a main control room of the nuclear power plant. The display device comprises power supply sequence parameter input parts A and B, display screens A and B, a display control part and a storage part, wherein the power supply sequence parameter input parts A and B are used for inputting display information used when the monitoring parameters of power supply sequences A and B are displayed; the display screens A and B are used for displaying the monitoring parameters of the power supply sequences A and B; the display control part is used for controlling the monitoring parameters of the power supply sequences A and B to be respectively displayed on the display screens A and B; and the storage part is used for storing the monitoring parameters of the power supply sequences A and B. The invention also relates to a display method of the post-accident monitoring system in the advanced control room of the nuclear power plant. By respectively displaying the monitoring parameters of the power supply sequence A (sequence A) and the power supply sequence B (sequence B) and storing the monitoring parameters through the storage part, the invention can effectively analyze the monitoring parameters of the post-accident monitoring system in the advanced control room of the nuclear power plant, which is convenient for an operator to analyze and treat the accident.