Wide-grading　loose　soils　(WGLS)　are　a　special　slope　deposit　that　often　serve　as　a　source　for　debris　flows　in　the　western　mountainous　area　of　China.　Previous　research　indicated　that　rainfall　infiltration　induced　the　migration　of　fine　particles　within　soil　slopes　and　lead　to　the　initiation　of　shallow　failure　and　subsequent　debris　flows.　Clearly,　soil　pore　structure　exerts　a　profound　influence　on　seepage　during　rainfall　infiltration,　which　is　closely　related　to　soil　permeability　and　corresponding　internal　erosion.　The　current　understanding　of　the　mechanisms　of　fine　particle　migration　is　limited　because　of　the　complexity　of　WGLS　micropore　structure.　The　challenge　lies　in　how　to　systematically　characterize　WGLS　pore　structure　so　that　it　provides　a　foundation　for　future　numerical　simulations　of　fine　particle　migration-induced　debris　flows.　In　this　study,　the　characteristics　of　WGLS　pore　structure　were　analyzed　quantitatively　using　scanning　electron　microscopy.　The　results　revealed　that　WGLS　predominantly　contained　micropores　and　mesopores.　The　pore　size　distribution　exhibited　a　bimodal　nature　with　one　peak　occurring　at　a　pore　diameter　of　12　mu　m　and　another　at　72　mu　m.　The　pore　complexity　of　all　samples　exceeded　0.75,　which　indicates　a　low　aspect　ratio　for　each　pore.　The　average　diameter　of　the　fine　particles　that　migrated　was　then　determined　with　a　laboratory　seepage　test.　A　preliminary　jamming　probability　analysis　based　on　three-dimensional　micropore　reconstruction　and　average　fine　particle　diameter　indicate　that　jamming　is　most　prevalent　along　the　slope.