Based on the motion law of equal -width slit steady f low, the seepage calculation model simulating concrete face slab joints and face slab with dense cracks is studied and established under the extreme condition t hat slabs are destroyed. With the calculation model, the seepage simulation calculation FEM of slab joints and face slab with dense cracks becomes possible, and thus an effective way for seepage analysis with FEM of CFRD under the extreme condition of slabs to be destroyed is provided. With the model, the seepage change law of CFRD under this extreme condition is also studied through an illustration.