Abstract: The problem of calculating electromagnetic quantities of the circuit in the complex cavity is studied in this thesis. A wave chaotic cavity is built, and its radiation and scattering parameters are obtained by testing. Based on RCM, the electromagnetic quantities of the circuit sensitive points are calculated with different microwave pulse width, interval, number and the loss factor. The results of calculation indicate that the coupling electromagnetic energy will be stronger when the target point is irradiated by pulse interference compared to that irradiated by power source. When the pulse energy is fixed, the coupling electromagnetic energy will show certain resonant characteristics with the pulses width, pulse intervals and pulse number, and it will be stronger when the interference pulse number is single compared to several pulse interference. The determination method of the target point more likely affected by electromagnetic interference of circuit is studied by using experiments.