The　structural　features　of　nano-sized　atom　clusters　and　their　long-rang　arrangement　in　the　Al-Ni-Ru　decagonal　quasicrystal　with　1.6　nm　periodicity　have　been　studied　and　compared　with　those　in　the　Al-Pd-Mn　decagonal　quasicrystal　on　the　basis　of　electron　microscopy.　From　the　perpendicular-space　analysis　of　the　tiling　obtained　in　a　wide　region,　we　conclude　that　long-range　arrangement　of　atom　clusters　in　the　Al-Ni-Ru　decagonal　quasicrystal　with　1.6　nm　periodicity　can　form　a　Penrose-tiling-like　quasiperiodic　structure　which　is　almost　free　of　linear　phase　strain.　In　contrast,　the　tiling　structure　of　the　Al-Pd-Mn　decagonal　quasicrystal　contains　heavy　phason　strain.　Our　results　clearly　show　that　atom　clusters　formed　in　the　Al-Ni-Ru　decagonal　quasicrystals　and　their　linkage　manner　are　completely　different　from　those　in　the　Al-Pd-Mn　decagonal　quasicrystal.　©　2005　Trans　Tech　Publications,　Switzerland.