In this paper the simulation of tapered slot antenna is considered. Because of the wideband characteristic of this type of antenna, it's better to use time domain methods for simulation. In this work we use three dimensional transmission line matrix method (3D TLM) and EPML-TLM algorithm for modeling PML boundary condition straightforwardly in TLM method. Finally the result of the simulation of a linear tapered slot antenna (LTSA) and a Vivaldi antenna which has the exponential tapering function is presented and compared by the result of other softwares and methods.