The invention discloses a pneumatic series high voltage switch comprising multiple levels of switches, wherein each level of switch comprises a low voltage electrode, a high voltage electrode and a trigger electrode, the low voltage electrodes and the high voltage electrodes of all switches are of an annular hollow structure, an insulating rod is arranged in the annular hollow structure, a plurality of the trigger electrodes are arranged on the insulating rod, each trigger electrode corresponds to a switch, and the insulating rod is driven by a cylinder piston to move along the axial direction of the annular hollow structure. The pneumatic series high voltage switch disclosed by the invention adopts an overall coaxial linear structure, therefore the inductance of the structure is small, the high voltage switch is triggered by mechanical movement, so that the reliability is very high, complete electrical isolation of a trigger control system and a main discharge loop is realized, the trigger control system is greatly simplified, a high voltage pulse system and a laser system, which are expensive and fragile, are omitted, thereby greatly reducing the cost and improving the environmental adaptability, and the pneumatic series high voltage switch is suitable for triggering military and compact MARX generators.