In order to ensure the normal operation of software electronic equipment and better guide the electromagnetic protection design of software electronic equipment, a set of computational models and numerical methods are needed to analyze the electromagnetic interference problems of electronic equipment. To this end, a new field-path hybrid time domain algorithm is adopted to simulate the electromagnetic interference of broadband electromagnetic signals to software electronic equipment in the time domain; the results are compared with those of the FDTD method to verify the correctness and efficiency of the algorithm. The average calculation time of FDTD is 478.3 min, while that of the field-path hybrid time domain algorithm is 46.5 min. The results show that the simulation effect of the field-path hybrid time domain algorithm is consistent with that of FDTD and saves a lot of memory and computation time, which proves the correctness and efficiency of the algorithm.