Rainfall　infiltration　is　a　key　factor　that　determines　the　active　earth　pressure　on　an　earth-retaining　structure.　Previous　investigations　on　the　stability　of　earth　retaining　structures　were　mainly　conducted　under　the　assumption　that　the　backfills　was　dry,　saturated,　or　subjected　to　a　steady　unsaturated　flow,　ignoring　the　time-varying　characteristics　of　the　rainfall　infiltration　process.　Based　on　the　upper　bound　theorem　of　limit　analysis,　this　study　conducted　a　stability　analysis　of　a　three-dimensional　(3D)　earth　retaining　structure　(ERS)　subjected　to　various　rainfall　infiltration　patterns.　An　analytical　model　that　was,　capable　of　calculating　the　pore　water　pressure　distribution　due　to　rainfall　infiltration,　was　employed　to　calculate　the　time-dependent　pore　water　pressure　change　of　unsaturated　soil.　A　horizontal　slice　method　was　employed　to　take　into　account　the　change　of　effective　unit　weight　of　soil.　Afterward,　an　analytical　expression　of　the　active　earth　pressure　coefficient　is　derived　from　the　energy　balance　equation.　The　effects　of　the　3D　characteristics　of　ERSs　and　rainfall　patterns　on　the　active　earth　pressure　coefficient　and　the　failure　pattern　of　ERSs　were　investigated.　It　was　found　that　compared　with　plain　strain　conditions,　the　3D　characteristics　of　ERSs　lead　to　a　lower　value　for　the　active　earth　pressure　and　better　stability.　The　rainfall　patterns　not　only　directly　determined　the　stability　and　active　earth　pressure　of　an　ERS,　but　also　played　a　dominant　role　in　critical　failure　pattern　of　the　ERS.