In the event of an earthquake, local site conditions such as soil characteristics, dimension of topographic irregularities, seismic bedrock depth, etc. and also characteristics of incident wave have important effects on seismic ground response. In this study, Finite Element Method (FEM) coupled to Viscous Boundaries is used to evaluate the effect of empty two-dimensional valleys on amplification or attenuation of seismic waves. Parametric studies carry out and the effects of dimension of the topography, frequency of the incident wave and bedrock depth on the seismic ground response are considered using non-linear method in a time domain analysis. Results are shown by means of horizontal and vertical amplification ratio in valley span and its surrounding area. It is concluded that displacement variation on ground surface due to topographical effects is a considerable factor to select a site location or design structures in the valley mount and its surrounding area.