In previous studies on reflection tomography imaging with terahertz wave, only parallel interfaces were considered. In this article we report the numerical simulation on reflection tomography imaging with terahertz wave of nonparallel interfaces inside the sample. The reconstructing algorithm is given according to the physical model and the correlative reconstructing software is compiled. The results show that the reconstructing method of nonparallel interface is feasible. The analysis indicates that the reconstructing errors result from approximate treatment and accumulative error. The approximate treatment method of the curve contour is discussed. If the curvature radii at all points are large, the curve can be treated by cutting it into several line segmeants. The factors affecting longitudinal resolution are analyzed finally. The results show that the longitudinal resolution becomes worse as the pulse width of input pulse becomes larger. The longitudinal resolution can reach sub-millimeter size usually.