Aiming at the problem of multiple false alarm signals of radar equipment in complex electromagnetic interference, in order to get the influence law of key parameters of radar equipment on false alarm signals, and to reveal the essential causes of false alarm signals, taking a type of stepper frequency ranging radar as the test object, this paper theoretically explains the mechanism of false alarm interference and the imaging characteristics of false alarm targets. Combining theoretical and experimental measurements, single-frequency continuous wave is selected as the source of electromagnetic interference, and the test method of injecting equivalent alternative electromagnetic radiation is adopted to summarize and generalize the influence of the critical radar parameters including frequency hopping interval and stepping frequency on the false alarm signal. The results show that the single-frequency electromagnetic interference of the test radar generates false alarm signal. When the frequency stepping of the tested radar is selected as 10 kHz and the frequency hopping time is 0.05 ms, the variation of false alarm level with interference frequency offset is relatively stable, and the signal amplitude loss is relatively small. The values can be used as the optimal control parameter values, and on this basis, it can provide technical support for subsequent experimental evaluation of radar equipment in multi frequency electromagnetic environments.