Abstract: Three Gorges Reservoir, as the main area of the National 13th Five-Year Plan for the Prevention and Control of Geological Disasters, is faced with outstanding problems of geological disasters, especially the area from Wanzhou to Wushan, which is a concentrated development area of geological disasters, with more than five thousand geological disasters spots. Taking background checking, risks evaluating and forecast researching as the main line, the authors have obtained some new understanding about the mechanism, background conditions of regional geological disasters and geological disaster risk assessment in urban area, through the project work in 2019. Firstly, the background conditions of geological disasters were summarized from geological material characteristics, occurrence conditions and influencing factors. Secondly, the formation and evolution mechanism of geological disasters was identified from geological deposition history, landform evolution and micro-landform transformation. Thirdly, the hazard-affected body were automatically extracted through the combination of optical remote sensing and low-altitude aerial photography of UAV. Fourthly, the geological disaster risk assessment method based on slope units was formed, and the geological disaster risk assessment of Dazhou town in Three Gorges Reservoir area was completed. These results play an exemplary role in supporting and serving local disaster prevention and control, and guiding geological disaster risk assessment.