The invention provides an impulse voltage generator. The generator comprises a rack, a capacitor, an insulation pull rod, an insulation synchronization belt and a discharge apparatus. The rack comprises a base plate 105, an insulation support column, an insulation crossbeam 103 and a conductive seat. The discharge apparatus comprises a metal block, a conductive tension spring and a conductive belt. During charging, capacitors, the capacitor and the conductive belt, the capacitor and the conductive seat and the like are disconnected so as to realize the charging. During discharging, the insulation synchronization belt moves so as to drive the insulation pull rod to move and drive the metal block to move. When the metal block moves to an adjacent capacitor pole, a loop is formed between all the capacitors and the conductive seat so that positive and negative electrode discharge of the capacitors and discharge to the ground are realized. Discharge time of the impulse voltage generator is short and structure operation is stable and reliable.