Abstract: According to the technique requirements of high intensity electromagnetic pulse radiation effect test for electronic information equipment, considering the defect of high expense and fixed test frequency point and radiated intensity for traditional direct radiation effect tests, a new injection test method based on differential mode directional injection and linear extrapolation is put forward. The supporting test equipment with signal injection and monitoring function is developed by adopting the design scheme of directional couplers cascade and strong coupling. The equivalent injection waveform acquisition method is presented based on the frequency domain transfer function method. On the basis above, the test method procedure of using differential mode directional injection as a substitute for high intensity electromagnetic pulse radiation is summarized. The data link TR component is selected as equipment under test. The test results verify the validity of the differential mode directional injection equivalent test method.