As the main material in constructing dams,arching mechanism in compacted rockfill is aways the focus of safety problem in compacted rockfiu dams. Compacted rockfill has different engineering characteristics according to stack forms and constructing techniques,and the failure of compacted rockfill conforms to Coulomb_Mohr criterion.Compacted rockfill is the main material in protecting embankment for the migration movement in Fuling city zone.The arching action is theoretically studied and numercally modelled especially for constructing techniques.It is found out that the arching action begins and numerically of settlement and burdens part of load and deadweight of upper soil.Earth pressure applied to the arch is smaller than the weight of overburden.