Based on the field surveys and laboratory analyses on seven mountain-river reservoirs of the Three Gorges, Ertan, Baozhusi, Dachaoshan, Manwan, Tianshenqiao Yiji and Zipinpu, four types of bank failure are identified as erosion, collapse, slide and flow. Their causes and characteristics are explored and the type and structure distribution probability is calculated among the seven reservoirs. It is revealed that bank failure in a mountain-river reservoir occurs mainly in the form of collapse and slide and at a residual slope.