Abstract: Cavity system-generated electromagnetic pulses (cavity SGEMP) were experimentally studied by exposing a cylindrical cavity to the Xray environment of a pulsed power facility at Institute of Fluid Physics, China Academy of Engineering Physics. The electric fields in the cylindrical cavity were measured using a netlike antenna, and a finite differencetime domain (FDTD) particleincell (PIC) code was applied to simulate the cavity SGEMP in the cylindrical cavity. The gas in the enclosure could reduce the electric fields, which could be enhanced by increasing the dose rate.