Abstract: The dielectric time-domain physical optics (TDPO) is proposed to calculate the time-domain scattered field of electrically large homogeneous dielectric targets. The Fresnel reflection coefficients are applied to the frequency-domain physical optics (PO) approximation, and formulae of the dielectric TDPO are derived through the inverse Fourier transform. Thus the conventional TDPO is extended to analyze the homogeneous dielectric objects. The technique for shadowing is discussed when the target is modeled with triangular facets. The transient scattering and wideband radar cross section (RCS) of several examples are given, of which results agree well with those obtained by other methods, which demonstrates the validity of the dielectric TDPO.