Slope failures are very common natural problems in the mountainous terrain due to the steep topography, improper landuse and adverse climatic conditions. In every geohazard study, detailed investigation on the geological structures, surface features and other related variables will be carried out. This paper discuss the impacts of geological and weathering properties as environmental factors for assessing slope failures in mountainous terrain. A case study from Dam Thuy commune, Trung Khanh county, Cao Bang province is used to illustrate the dynamic interaction between landsliding factors and slope failures. Regional survey results include underlying geology, surface forms and features, and weathering process in study area. Methods used to analyse the geologic, geomorphic and weathering characteristics of Backan town area include a combination of remote sensing image interpretation, field mapping, soil/stratigraphic descriptions, and the use of previously published surveys. The collected data then can be combined to create landslide hazard and risk maps for study area.