Based on analyzing three cases, i.e., water stone riprap exploration of bank protection embankment, underwater exploration of concrete grid and gravel layer, and river waters yard landslide detection, the authors tried to illustrate the effect of the geological radar exploration in the freshwater of shallow water. The impacts of conductivity, dielectric constant and frequency detection were studied by using the antenna to an environment that the object detection is in. GPR fills the gaps of engineering investigation in the shallow water, and research on GPR and test in the non-ater area are of reference value.