A　spatially　pinned　surface　plasmon　is　constructed　by　connecting　a　gold　nanoshell　grating　with　a　planar　gold　nanofilm,　forming　a　periodical　array　of　gold　nanoloops.　Dramatic　electric　field　modulation　and　high　charge　carrier　density　on　the　contact　sites　enable　balanced　plasmonic　electron　distribution　over　the　spatially　pinned　nanostructures.　Compared　with　its　counterpart,　spacer-supported　double-layer　surface　plasmon　polaritons　(SPPs),　the　pinned　structure　not　only　changed　the　electronic　oscillation　channels　but　also　short-circuited　the　propagating　SPPs　at　the　top　and　bottom　interfaces.　Ultrafast　spectroscopic　dynamics　identified　a　much-extended　relaxation　lifetime　of　the　pinned　plasmon　and　revealed　a　holding　time　as　long　as　1.3　ps　for　the　double-layer　SPPs,　which　was　sustained　by　microcavities　based　on　distributed　optical　feedback.　These　results　introduced　a　new　type　of　surface　plasmon　and　a　new　design　of　time　retarders　for　optical　logic　circuits.