Abstract: In order to study the characteristics of the needle-plate corona discharge induced by the electromagnetic field in the vacuum environment, a simulation test system of corona discharge induced by the electromagnetic fields, such as the electromagnetic field generator, the vacuum system, the high voltage power supply, and the dynamic potential tester, is developed. The system can realize a low vacuum environment of 80 Pa, and we can use the system to carry out the corona discharge test under the action of the electromagnetic field. The change laws of the threshold voltage of corona discharge induced by electromagnetic field are obtained. The experimental results show that when the temperature, humidity and other environmental factors keep unchanged, the normal discharge threshold is -590 V. When the pressure of the vacuum tube is 80 Pa, the negative high voltage of electrostatic discharge could release a voltage from 10 kV to 20 kV. The electromagnetic pulse acts on the inner of the vacuum tube in the charging area, the discharge threshold will reduce 90-180 V.