Uncertainty is inevitable in the safety monitoring and evaluation process of earth-rock dam. Such uncertainty makes the accurate reflection of the running status of earth-rock dams of traditional safety assessment results impossible. Thus, this study proposed a safety assessment model of earth-rock dams based on the combination weighting method of ideal point and the cloud theory model. The proposed model was used to scientifically solve the uncertainty during the safety assessment of earth-rock dams. Real and reliable weights of indexes were determined using the combination weighting method based on the ideal point. Then, the safety evaluation grade ranges of each evaluation index were divided on the basis of the measured data. These grade ranges were "softened" by combining cloud theory. The proposed safety assessment model was applied to an earth-rock dam in the reservoir of a pumped storage station in Tai'an City, Shandong Province, China. Results demonstrate that: (1) the proposed model can effectively solve fuzzy and random problems during the safety assessment of earth-rock dams, and (2) the results show that the safety of the investigated earth-rock dam is in a normal running state. This outcome reflects the actual conditions of the earth-rock dam. The proposed model provides references in the diagnosis and decision making in the earth-rock dam management department.