Abstract: In response to the demand for detecting hidden danger in earth embankment of a certain riverbank, combined with the composition characteristics of the riverbank earth embankment and based on the time-domain difference theory, the GPRSIM software was employed to conduct forward modeling of the geological radar spectrum for different hidden dangers. The simulation results were compared and analyzed with the spectrum obtained from on-site detection. It was discovered that: in the sections with good embankment conditions, the medium distribution of each structural layer was uniform, and the geological radar reflection wave spectrum showed continuous phase axes, with continuous and stable reflection interfaces of the embankment and no significant fluctuations; when the settlement of the embankment was relatively small, the geological radar reflection wave spectrum showed continuous phase axes but with a concave-shaped characteristic; when the settlement of the embankment was significant or the soil was loose, the geological radar reflection wave spectrum showed discontinuous phase axes, with weak amplitudes in the abnormal areas, a low frequency of the radar waveform, and loose soil was prone to cause significant settlement and voids beneath the concrete surface layer. The forward modeling results were largely consistent with the on-site measured and verified results of the geological radar.