Abstract: A new equivalent numerical model was developed for evaluating the behavior of extrusion-sidewall adopted in CFRD (Concrete-Faced Rockfill Dam) and particularly its effect on the stress-deformation behavior of the concrete slab. It is composed of an equivalent plate and an equivalent interface. The equivalent plate is assumed to be linearly elastic and thus it is described with a linear elastic constitutive model. The equivalent interface is described with the Tsinghua elasto-plasticity damage interface constitutive model. All the model parameters can be easily determined. The equivalent numerical model was applied to two and three dimension FEM analysis of a practical CFRD. The results show that the equivalent numerical model and related numerical analysis method is effective to simplify the stress-deformation evaluation of CFRD adopting extrusion-sidewall technology with a sufficiently good degree of accuracy.