In the northwest section of the lesser Khingan range, located in the high-latitude permafrost region of northeast China, landslides are a frequent occurrence, due to permafrost melting and atmospheric precipitation. High-density resistivity (HDR) and ground-penetrating radar (GPR) methods are based on soil resistivity values and characteristics of radar wave reflection, respectively. The combination of these methods, together with geological drilling, can be used to determine the stratigraphic distribution of this region, which will allow precise determination of the exact location of the sliding surface of the landslide. Field test results show that the resistivity values and radar reflectivity characteristics of the soil in the landslide mass largely differ from those of the soil outside the mass. The apparent resistivity values exhibit abrupt layering at the position of the sliding surface, with a sudden decrease in apparent resistivity. In addition, the radar wave shows strong reflection at the position of the sliding surface, where the amplitude of the radar wave exhibits a sudden increase. Drilling results indicate that the soil has high water content at the location of the sliding surface of the landslide mass in the study area, which is entirely consistent with the GPR and HDR results. Thus, in practice, sudden changes in apparent resistivity values and abnormal radar wave reflection can be used as a basis for determining the location of sliding surfaces of landslide masses in this region.