The invention relates to a device and a method for monitoring internal discharge of materials for a ground simulation satellite, which belongs to the technical field of space. The device comprises a vacuum chamber, an electronic gun, a sample base, a vacuum wall, a resistor, a conducting wire, an outer shielding layer, an insulation layer, a vacuum pumping system and an oscillograph. The method comprises the following steps that: a sample is fixedly arranged inside the vacuum chamber to be connected with a discharging signal circuit; the electronic gun is started after the vacuum chamber is vacuum pumped, the electronic gun transmits high-energy electron beams onto the surface of the sample, and the oscillograph is simultaneously started; and when the high-energy electrons are accumulated inside the sample to be saturated, the internal discharge phenomenon occurs, and the discharge waveform is displayed on the oscillograph. Due to the adoption of the device and the method, the electrification environment inside a satellite can be simulated on the ground, the internal discharge pulse can be monitored, so the internal discharge performance of the materials for the satellite can be evaluated.