Ultra-wideband (UWB) through-wall imaging radar is a promising technique and can be widely used for detecting and locating moving people through obstacles. Through-wall imaging radar employs coherent and non-coherent imaging techniques. In this paper we focus on a one-transmitter two-receiver non-coherent radar system. Analytical formulations of the target localization are given under the condition of both the absence of the wall and the presence of the wall. This paper also provides the cross-range resolution analysis and the supporting FDTD simulation results.