Abstract: Since reinforce concrete walls of buildings have important influences on the reflection,transmission and diffraction of electromagnetic waves,it is critical to study the shielding effects of reinforce concrete walls for civilian wireless communication and electromagnetic attacking and defending in military situation.Thus,the shielding effects of reinforce concrete walls are analyzed by using FDTD and Fourier Method.Based on the analysis of the numeral results,it is shown that resonance will occur in reinforce concrete walls and the relationship of the shielding effects with periodic and diameter of rebar lattice,thickness,dielectric constant,conductivity of concrete wall,and so on is derived,which will be useful for the associated researches.