The invention is suitable for a power equipment online digital detection and monitoring technology, belongs to the key technical field of million-kilowatt nuclear plants, and provides a universal analog quantity plate detection system for a nuclear plant and a method. The system comprises a stress test machine cabinet, an upper computer, a peripheral component interconnect (PCI) expansion for instrument (PXI) test system, plates and a plate power supply. The stress test machine cabinet is used for installation of the upper computer, the PXI test system, the plates and the plate power supply. The upper computer is used for sending control commands to the PXI test system and processing test data fed back by the PXI test system. The PXI test system is used for controlling the plate power supply to output current excitation signals and voltage excitation signal to the plates according to a predefined time shaft, collecting test data of the plates, and outputting the test data to the upper computer. The detection system and the method enable people to find quality defects of the plates in an early stage in advance, and improve accuracy of detection of the plates.