A new structure system for the high rockfill dam with earth core built on deep overburden layer is proposed, which is to construct concrete slab directly on the deep overburden layer, and to build concrete cut-off wall in the large corridor in the concrete slab. The cut-off wall in deep overburden layer, the concrete slab and the upper dam constitute a complete anti-seepage system. The new dam structure is analyzed through finite element calculation, and the stress and deformation law of this structure are acquired. Moreover, the safety and adaptation of the structure are evaluated to be feasible.  