The disclosure relates to a high-voltage generator for connecting an X-ray generation device. The high-voltage generator comprises an inverter bridge, a first resonant branch, a transformer, a secondresonant branch, and a rectification circuit. The inverter bridge consists of a first bridge arm and a second bridge arm; and the first bridge arm or the second bridge includes at least two switchingtubes connected in series. The first resonant branch is coupled to the output terminal of the first bridge arm in series. The transformer is coupled between the first resonant branch and the second bridge arm in series. The second resonant branch is coupled to the two ends of the transformer in parallel. The rectification circuit connected with the transformer is used for providing an output voltage for an X-ray generation device. In addition, the invention also relates to a control method of the high-voltage generator.