The invention belongs to the field of high-power pulses, and particularly relates to a closed planar three-
electrode spark switch and a preparation method thereof. The closed planar three-
electrode spark switch sequentially comprises a bottom layer PCB, a circuit layer, a PP layer and a top layer PCB, and the bottom layer PCB is a substrate of a switch circuit layer; the circuit layer comprises ananode, a
cathode, a trigger
electrode and a bonding pad connected with the
anode, the
cathode and the trigger electrode; pad windows are formed in the PP layer corresponding to the bonding pad, and electrode windows are formed in the PP layer corresponding to the electrodes; a bonding pad groove is formed in the position, corresponding to the bonding pad, of the top layer PCB, and a blind grooveis formed in the position, corresponding to the electrode, of the top layer PCB; the PP layer is used as a
dielectric layer for bonding the top layer PCB and the bottom layer PCB, and the bottom layerPCB and the bottom layer PCB are laminated by using the PP layer, so that a cavity is formed in the whole switch. The planar three-electrode spark switch is made into a closed type by using a printedcircuit board technology, so that the
working environment of the switch is stabilized, the high overload resistance of the switch is improved, the cost is greatly reduced, and the planar three-electrode spark switch can be widely applied to
pulse power systems such as exploding foil exploders and electric cannons.