The invention discloses an adjustable high-impedance miniaturized high-voltage diode which comprises an insulator, an anode cylinder, a cathode rod, a cathode base, an annular cathode and a drift tube, wherein the anode tube and the drift tube are arranged coaxially, main guide magnetic fields are coaxially arranged on the outer surfaces of the anode tube and the drift tube; the cathode rod, the cathode base and the annular cathode are coaxially connected into a whole in sequence and are coaxially arranged with the anode cylinder and do not overlap with the anode cylinder in the axial direction, supplementary magnetic fields are coaxially arranged on the cathode rod, and the axial distance between the annular cathode and the anode cylinder can be adjusted. The high-impedance performance ofa high-voltage diode can be achieved, the design is ingenious, and the structure is simple and easy to realize. The adjustable high-impedance miniaturized high-voltage diode is convenient to use, lowin manufacturing and maintenance cost, small in size and light in weight, low in energy consumption and wide in application prospect in the development of high-impedance microwave devices, especiallysuitable for being applied to a mobile platform. Furthermore, the adjustable high-impedance miniaturized high-voltage diode has outstanding substantive features and remarkable progress and is suitable for large-scale popularization and application.