Taking a hydropower station in the upper reaches of Lancang River as an example, the detailed survey, statistics and analysis of the exploration Adit in the area are carried out, and the location, lithology, occurrence, structure and characteristics of the toppling deformation body are analyzed in detail. It is found that the toppling deformation of the reservoir bank is serious. With the passage of time, the dumping rock experience further deformation under the internal and external force. It seriously restricts the construction of hydropower station. The deformation of the correct methods of evaluation is of great significance to the safety of the bank. With the help of UDEC software, the maximum horizontal displacement, the deformation area and the total displacement are used to evaluate the toppling deformation. It is concluded that the method of evaluating the deformation of rock mass with total displacement is more accurate.