Time domain modeling in electromagnetics has been of interest since the advent of Maxwell's equation s. Despite the fact that, historically, because of less computational complexity of frequency domain, most analysis was performed in this domain, with the advancement of technology and processors speed, time domain electromagnetic analysis is done with less difficulty. In the case of complex electromagnetic problems and nonlinear or time variant problems, time domain analysis is of particular importance. In multilayer structures that are important issues in electromagnetics, time domain analysis is preferred. The reason for this is that more applications of multilayered media structures such as design and analysis of microstrip antenna and circuits, optical integrated circuits, geophysics prospecting, wave propagation between the land and atmosphere and also remote sensing contain wide band excitation or nonlinear elements. Time domain methods are divided to two group; Differential Equation (DE) methods and Integral Equation (IE) methods. Since DE methods are almost time consuming and need a large memory for storing and on the other hand, IE methods are easily applicable to non-linear problems, IE methods used for analysis of multilayered structures. By choosing the appropriate formulation integral equation for a given structure, it is necessary numerical technique for solving integral equation to be adopted. Method of Moment (MoM) is one of the most applicable numerical techniques in electromagnetic problems especially, for PEC structures. In this thesis, time domain MoM analysis of PEC planar surfaces in multilayered media by complex time method done. Integral equation of the problem contains the Green's function of multilayered media that due to fluctuating nature and slow attenuation cannot be solved directly. ‌By using complex time method, the Green function in spatial domain expressed by exponential series of spatial variable. T hen the integral can be approximated in case of some limited sentences using Sommerfeld Identity . Key word: Time Donain Analysis, Multilayered Media, Integral Equations, Complex Tima Method