Abstract: The EMP radiator is the key part of the portable measurement equipment of electric field shielding efficacy . In this dissertation a plan of a small-sized EMP radiator is provided, and the radioactive near field emitted by radiator is analyzed by the finitedifference timedomain algorithm. It is demonstrated that if the high voltage pulse generator produces voltage pulse of he form of double exponential function, the waveform of nearfield produced by the EMP radiator will be double exponential waveform. The nearfield parameters accord with measurement equipment requirements. So the plan of EMP reaiator is feasible.