The determination method of Pulse Current Injection(PCI) waveform parameters of System Generated Electromagnetic Pulse(SGEMP) is studied by using electromagnetic norm. When the load is high and low resistance respectively, the typical response waveform of SGEMP is double exponential waveform and Gaussian waveform. Considering the difference between the rise time, the peak value, the energy and the charge carried by the equivalent waveform and the response waveform, the equivalent waveform parameters of pulse current injection are studied. The results show that the square wave equivalent waveform can simulate the response waveform according to the characteristics of the response waveform and electronic system. Therefore, it is possible to use electromagnetic norm to parameterize the equivalence of SGEMP response waveform, and the equivalent waveform can be easily generated in laboratory, which provides a new way for the study of SGEMP by the current injection method.