When　a　retaining　wall　is　adjacent　to　a　natural　slope,　the　overturning　of　the　wall　is　usually　caused　by　a　yielding　foundation.　At　the　point　of　overturning,　the　narrow　backfill　behind　the　wall　has　reached　the　active　limit　state.　However,　in　previous　studies,　the　foundation　conditions　of　the　retaining　wall　were　not　fully　considered　when　the　earth　pressure　on　the　retaining　wall　with　the　narrow　backfill　was　calculated.　To　comprehensively　consider　the　stress　state　of　the　retaining　wall,　the　finite-element　limit　analysis　method　was　employed　to　study　the　failure　mode　of　a　retaining　wall　adjacent　to　a　natural　slope.　The　simulation　results　indicate　that　the　sliding　surface　starts　from　the　wall　heel,　with　one　side　developing　at　the　surface　of　the　natural　slope　and　the　other　developing　in　the　ground　in　front　of　the　wall.　Based　on　this　failure　mechanism,　a　slip-line　computational　model　for　the　retaining　wall　was　established.　When　the　slip-line　solution　was　compared　with　the　finite-element　solution,　the　results　were　in　good　agreement.　The　plastic　zone　of　the　soil　was　determined　by　the　slip-line　field.　In　addition,　the　slip-line　solution　gave　the　active　earth　pressure　of　the　narrow　backfill,　the　passive　earth　pressure　of　the　soil　in　front　of　the　wall,　and　the　foundation　bearing　capacity.　Moreover,　several　extensive　parametric　studies　were　conducted.　Thus,　the　shape　of　the　narrow　backfill,　the　rough　soil-wall　interface,　and　the　low-strength　backfill　are　all　conducive　to　reducing　active　earth　pressure　on　a　retaining　wall.