Twodimensional oblique incidence problem of layered half space is generally translated into onedimensional condition to process, however, the effectiveness of this treatment method is closely related to the size of the angle of incidence. In this paper, the oblique incidence angle size of a onedimensional corrected processing method is researched, in the same time, using this method the impact on the time domain, frequency domain characteristics of the reflected wave is researched caused by dielectric constant , conductivity and dispersion characteristics of medium. The conclusion has a good guidance for FDTD analysis of layered half space and engineering applications such as the inversion of ground object.