On　the　top　of　TiO2　nanotube　arrays,　nanograss　structure　may　be　generated　due　to　electrolyte　composition,　the　oxidizing　condition　and　the　size　of　nanotube　in　anodic　oxidation　process.　TiO2　nanoring/nanotube　hierarchical　structure　with　smooth　surface　was　fabricated　by　two-step　anodic　oxidation.　Growth　mechanism　and　optical　absorption　properties　of　the　resulting　TiO2　nanoring/nanotube　hierarchical　structure　were　investigated　by　controlling　oxidation　time　of　the　anodic　oxidation.　The　results　show　that　the　growth　of　nanotubes　is　limited　by　regular　hexagonal　nanocaves　on　the　surface　of　Ti　substrate　during　the　second　step　of　anodization　resulting　in　formation　of　TiO2　nanoring/nanotube　hierarchical　structure.　Meanwhile,　the　nanorings　provide　the　support　of　their　internal　nanotubes　to　avoid　formation　of　nanograss　structure.　Absorption　spectrum　of　TiO2　nanoring/nanotube　hierarchical　structure　exhibits　oscillating　peaks　in　visible　light　region,　due　to　the　interference　between　lights　reflected　from　the　top　of　nanorings　and　the　bottom　of　Ti　substrate.　Based　on　the　relationship　between　oscillation　peaks　shape　and　film　thickness,　the　maximum　optical　penetration　depth　of　TiO2　nanoring/nanotube　hierarchical　structure　is　estimated　to　be　similar　to　2　mu　m.