A constant current high voltage power supply is described, which is used to charging the capacitor banks quickly and efficiently in pulse power technology. The three-phase alternating current is rectified with the half-controlled bridge mode of Silicon Controlled Rectifier(SCR), then, is imported into the constant current network consisted of two SCR, storage energy inductance, continuous current diode and Hall sensor, thirdly is changed inversely into 1kHz A.C by the self-controlled SCR bridge circuit, finally, is put into a step-up transformer and rectified by SCR.