The invention relates to a high power high voltage generator which comprises a main circuit and a control portion. The main circuit adopts insulated gate bipolar translators (IGBTs) as an inversion module to form a full bridge inversion circuit. The output end of the full bridge inversion circuit is connected with a resonant circuit and a booster transformer to output high voltage. The control portion comprises a kilovolt (KV) double-ring adjusting circuit, a phase shift controller, a complex programmable logic device (CPLD) and an IGBT drive and protection circuit. The input end of the KV double-ring adjusting circuit receives KV feeding value and current feedback signals and voltage feedback signals of the main circuit, the output end of the KV double-ring adjusting circuit is connected with the CPLD through the phase shift controller, and output signals of the CPLD are transferred to grid electrodes of each IGBT in the main circuit through the IGBT drive and protection circuit. The high power high voltage generator improves inversion reliability, simultaneously reduces product cost, reduces the radiating mode, prolongs service life of the IGBT, can quickly build KV output and maintains high accuracy.