The invention provides a parallel plate electrode electromagnetic field irradiation discharge system with adjustable vacuum degree. The system comprises an electromagnetic field irradiation device, aparallel plate discharge device, a vacuum environment simulation device and a detection device. The electromagnetic field irradiation device is arranged on the outer side of a vacuum environment simulation device to simulate the irradiation condition of an external complex electromagnetic environment. The parallel plate discharge device can simulate the discharge condition of different parallel plates in the actual environment. The vacuum environment simulation device improves the repeatability of an experiment, and is combined with the detection system to constitute the electromagnetic fieldirradiation induced parallel plate discharge system under a vacuum environment. The system is used to study related technologies of electromagnetic radiated emission, the effects of electromagnetic radiation on the induced parallel plate discharge system and other issues, provides accurate data for a protective device, and reduces safety risks of a railway system.