Abstract: The mountainous and hilly area of South China has a large geographical span, with complex geological hazard pregnant background and diverse disaster modes, and it is an area with dense distribution of geological hazards in China. Aiming at the potential risk of geological hazards in mountainous and hilly areas of South China, the authors in this paper systematically analyze the climatic dynamic characteristics and geological structure background of geological hazard in mountainous and hilly areas of South China, based on progress of the implementation of “geological hazard investigation project in mountainous and hilly areas of South China” by China Geological Survey. The disaster models of typical geological hazards and the demonstration results of multi-scale risk inve-stigation and evaluation are analyzed, and the formation mechanism and provenance erosion mechanism of typical typhoon geological hazards in southeast coastal areas, karst collapse in South China, moraine soil debris flow in southwest Alpine mountainous areas and post fire debris flow in Western Sichuan Plateau are revealed. On this basis, a multi-scale geological hazard risk assessment demonstration based on counties, key towns and typical disaster points in mountainous and hilly areas of South China was carried out, and the relevant results were applied in the planning and route selection of major projects in Southwestern China and the relocation site selection of counties.