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 finitedifference timedomain algorithm. It is demonstrated that if the high voltage pulse generator produces voltage pulse of he form of double exponential function, the waveform of nearfield produced by the EMP radiator will be double exponential waveform. The nearfield parameters accord with measurement equipment requirements. So the plan of EMP reaiator is feasible.