The cloud model is a qualitative concept and its quantitative expression of uncertainty between the conversion models, and it can combine concept's fuzziness and randomness, to solve the problem of uncertainty. This article uses cloud models and cloud reasoning to predict the Earth-rock fill dam deformation, and initially solved the Earth-rock fill dam deformation prediction of the existence of fuzzy and stochastic problems. The results show that the prediction accuracy of the method is higher, and it is consistent with the actual values.