Through　a　series　of　model　tests　accomplished　by　Particle　Image　Velocimetry　analyses,　this　study　presents　the　visualization　of　the　displacement　field　of　the　narrow　soil　behind　retaining　structures　under　translational　mode.　The　progressive　development　of　failure　mechanisms　and　active　earth　pressure　are　measured　in　the　process　of　tests.　Finite　element　limit　analyses　are　supplementally　carried　out　to　investigate　and　verify　the　ultimate　failure　mechanism　and　active　earth　pressure　acting　on　retaining　structures　as　the　tests.　Furthermore,　this　study　carried　out　parameter　studies　on　the　development　of　failure　mechanisms　and　active　earth　pressure　with　different　aspect　ratios,　inclinations　of　the　existing　structure,　and　backfill　surface　surcharge.　Experimental　and　numerical　results　show　a　reasonable　verification　of　each　other.　With　the　increase　in　backfill　spacing,　the　failure　mechanism　of　backfill　turns　from　reflective　shear　bands　into　a　single　shear　band,　and　the　earth　pressure　exerted　on　the　retaining　structure　increases.