The utility model relates to a 20-pulase multi-waveform impulse generator, which comprises a transformer charging device, 20 body capacitor energy storage devices, 20 anti-electric sphere gaps, 20 wave modulating devices and a sample box, wherein the transformer charging device, the 20 body capacitor energy storage devices, the 20 anti-electric sphere gaps and the sample box are sequentially connected; the transformer charging device and the 20 body capacitor energy storage devices are connected to the 20 wave modulating devices; the 20 body capacitor energy storage devices are arranged in a parallel connection mode, the 20 anti-electric sphere gaps are connected in a parallel connection mode, and the 20 wave modulating devices are arranged in a parallel connection mode; and the sample box is grounded, and the 20 wave modulating devices are connected to a grounding line of the sample box. The number of lightning strikes is 1-20, multi-path high voltage discharging can be realized, and the time sequence is accurate and controllable at the same time.