A high voltage power supply and a high voltage power control method thereof. The high voltage power supply includes a high voltage generation part to generate a high voltage, and a pulse width modulation (PWM) generation part to generate a pulse width modulation signal according to an output control value and to control the high voltage generation part to generate the high voltage using the generated pulse width modulation signal, when a high voltage output setting signal having the output control value is received by the PWM generation part to indicate the high voltage to be generated. Therefore, it is possible to automatically output a high voltage as desired without requiring an offline setting. In addition, although a voltage set and/or an output load are changed, the changed voltage set and/or the output load are automatically compensated so that a constant high voltage output can be output with a variety of different devices having different loads and power requirements.