The　construction　of　3D　localized　surface　plasmons　(LSPs)　in　infrared　using　curved　gold　nanoshell　(AuNS)　cylindrical　ridges　is　reported,　where　the　LSPs　are　found　to　be　established　through　electronic　oscillation　in　curved　trajectories　along　the　perimeter　of　the　cross-sectional　profile　of　the　AuNS　cylindrical　ridges.　Such　a　design　is　equivalent　to　an　extension　of　the　electronic　trajectory　length　or　plasmonic　electron-oscillation　distance　by　the　curvature　length　and　by　the　enhanced　electronic　scattering.　Strong　LSPs　are　measured　for　the　transverse　magnetic　polarization　perpendicular　to　the　extending　direction　of　the　AuNS　cylindrical　ridges　in　the　spectral　range　from　1.1　to　beyond　2.5　mu　m,　which　are　not　observed　for　the　transverse　electric　polarization.　Such　LSPs　are　strongly　dependent　on　the　perimeter　length,　the　curvature　angle,　and　the　thickness　of　AuNSs.　The　corresponding　mechanisms　are　verified　convincingly　by　both　the　experimental　and　theoretical　results.　These　discoveries　explore　new　approaches　to　designing　plasmonic　devices　in　the　infrared　using　nanoscale　structures.　The　3D　scheme　with　large　modulation　depth　not　only　facilitates　equivalent　extending　of　the　dimensions　of　the　metallic　nanostructures,　but　also　enlarges　interaction　volume　between　plasmons　and　molecules,　implying　applications　of　them　in　micro-/nano-cavity　lasers,　sensors,　or　optoelectronic　devices　based　on　plasmonic　enhancement.