Abstract: The response of electromagnetic pulse penetrating building walls is analyzed using FDTD and Fourier analysis method. The pulse responses within a wide frequency band are calculated based on periodic boundary condition and Gaussian pulse. Through the discussion of the calculated results, the influences of different walls are obtained, which will improve the electromagnetic shielding design to protect electronic equipments. The simulation results show that the rebar array works pretty well for shielding in low frequency, but the shielding effectiveness will become poor as the frequency increases. The periodicity of the frequency domain waveform in concrete walls indicates that there exists a lot of resonance frequency points and the transmission coefficients become comparatively higher on th