Unlike　conventional　homogeneous　nanograined　(NG)　materials,　gradient　structured　materials　combine　high　strength　and　ductility.　The　gradient　nanograined　(GNG)　structures　are　divided　into　three　zones　by　grain　size:　the　small-grained　zone,　the　transition-grained　zone,　and　the　large-grained　zone.　Molecular　dynamics　(MD)　simulation　is　performed　to　investigate　the　effect　of　the　widths　of　zones　on　the　strength　of　GNG　structures　with　different　grain　sizes.　The　simulation　results　reveal　the　strengthening　mechanism　of　GNG　structures　from　the　perspective　of　microstructure　evolution.　With　the　change　in　grain　size,　the　dominant　deformation　mode　changes　from　grain　boundary　(GB)　activities　in　the　mall-grained　zone　to　dislocation　slip　in　the　large　one.　The　inverse　Hall-Petch　phenomenon　is　observed　during　plastic　deformation.　Synergistic　strengthening　of　dislocation　and　heterodeformation　induced　(HDI)　can　be　achieved　in　the　structure　by　regulating　the　widths　of　zones　with　different　grain　sizes.