Long-term　irrigation　promotes　the　infiltration　of　water　in　the　thick,　stratified　loess　layer,　significantly　raising　the　groundwater　table　and　triggering　a　series　of　landslides　in　loess　platform　areas.　The　soil–water　characteristic　curve　(SWCC)　of　loess　buried　at　different　depths　affects　the　unsaturated　infiltration　process　and　is　intricately　connected　to　the　soil’s　microstructure.　The　SWCCs,　scanning　electron　microscope　(SEMs),　and　pore　size　distributions　(PSDs)　for　five　sets　of　undisturbed　loess　samples　at　depths　ranging　from　3.4　to　51.9　m　are　shown　in　this　paper.　The　results　indicate　that　the　fitting　parameter　air　entry　value　(AEV)　of　the　SWCC　rises　from　13.67　kPa　to　40.19　kPa　as　the　depth　increases　from　3.4　to　51.9　m.　And　the　saturated　volumetric　water　content　drops　by　10.9%,　with　a　notable　SWCC　shape　difference　between　the　transition　and　residual　zones　observed.　Additionally,　the　total　porosity　of　undisturbed　loess　falls　by　12%　when　the　depth　increases　from　3.4　to　51.9　m,　while　the　macropores　and　mesopores　reduce　by　3.6%　and　12.1%,　respectively.　These　findings　highlight　the　control　of　the　pore　structure　on　the　SWCC　and　emphasize　the　correspondence　between　the　SWCC　and　PSD.　The　conclusions　also　illustrate　that　the　compaction　effect　changes　the　microstructure　characteristics　of　loess,　thereby　affecting　the　soil’s　water　retention　behavior.　©　2024　by　the　authors.