Abstract: Sediment particles in natural rock with alarge number of connected cracks and faults, have some impact on the transportof groundwater and the variable permeability by creating micro-cracks anddamage zones around faults. In this paper, an experiment about seepageon the rock electro-hydraulic servo test system of MTS815.02, together withelectron micrograph of sandstone pore, is designed and used to investigatethe relationship between the variable permeability and the filling silt increating cracks. Results show that the permeability in cracked rockdecreases distinctly under the silt-induced effect. The permeability, along with thesediment particles in macro-fissures in the cracked rock to achievere-balancing of transport, gradually increases over time and eventuallystabilizes.