Understanding　the　shrinkage　behavior　of　bentonite　considering　physicochemical　effects　is　important　to　assess　the　efficiency　of　buffer　barriers　in　environmental　geotechnical　engineering.　In　this　paper,　shrinkage　experiments　were　conducted　on　Na-bentonite　specimens　prepared　with　salt　solutions　at　various　concentrations.　NMR　and　SEM　tests　were　conducted　to　study　the　moisture　distribution　and　structural　evolution　of　specimens　during　the　evaporation　of　water.　After　sample　saturation,　the　porosity　decreases　as　the　pore　water　salinity　increases　due　to　the　decreasing　swelling　deformation　with　pore　water　concentration　during　the　saturation　process.　During　drying,　the　shrinkage　deformation　of　compacted　bentonite　is　anisotropic,　with　larger　axial　strains　than　radial　strains.　At　the　fully　dried　state,　the　bentonite　specimen　prepared　with　distilled　water　is　the　densest　due　to　the　least　crystalline　salts　in　the　specimen.　At　the　microscale,　as　pore　water　salinity　increases,　pore　water　is　distributed　to　smaller　pores,　and　the　microstructure　is　more　aggregated.　The　saline　effect　on　water　retention　and　distribution　is　weakened　as　pore　water　evaporates,　originating　from　physicochemical　effects.　The　structure　is　also　more　aggregated　after　evaporation　of　pore　water.　Theoretically,　the　shrinkage　behavior　of　Na-bentonite　considering　the　influence　of　water　salinity　is　well　described　from　the　perspective　of　an　effective　stress-based　constitutive　relationship.　©　2023