Abstract: Behaviours of the Miaojiaba concrete-face rockfill dam (CFRD) built on river gravel foundation was evaluated by combining in-situ measurements and numerical analysis, and time variations and spatial distributions of its deformation and stress were examined and compared with those of normal CFRDs on rock foundation. Detailed field data were collected in this study using a deformation monitoring system for the stages of dam construction and initial reservoir filling plus one year period of normal operation. We also made 3D finite element simulations using back analysis of the model input parameters to assess the deformation and stress behaviours for these short stages and long-term operation. Comparison of the measurements and FEM simulations shows a good agreement between them. The main findings suggest that this dam is stable and performs well. This paper also presents a comparative analysis of CFRDs on river gravel foundation versus rock foundation, based on the deformation data of in-situ measurements of 12 CFRDs in service. The analysis shows that river gravels have a significant affect of dam deformation. In the case of river gravel foundation, settlement of the dam body and deflection of face slabs are much larger than those of normal dams and the locations of peak deformation move downward.