The utility model discloses an impulse voltage generator. The ignition ball assembly comprises a totally-enclosed shell, the shell isolates the ignition ball assembly from the surrounding environment;according to the utility model, the dielectric coefficient of the sphere gap gas is prevented from being directly influenced by water molecules in the air and the external temperature, and the circuit breaker arranged between two adjacent charging capacitors is a pneumatic switch, so that different charging voltages are distributed in a balanced manner, the synchronism of different levels of discharging unit assemblies is better, and the discharging efficiency is high.