To meet the demand of radar for miniaturization of transmitter, a miniaturized high-voltage power supply is designed for a certain type of TWT. The high voltage power supply adopts a phase shifted full bridge topology structure, and the high voltage rectifier circuit uses SiC diodes to improve the power density of the power supply. The miniaturized pulse high-voltage power supply has been developed, with a cathode voltage of -6.5 kV, a maximum working pulse width of 2 ms, and a peak power of 1600 W. The joint test with traveling-wave tube shows that the output RF power of TWT is stable during pulse operation. The test results verify the feasibility of the design method.