Understanding　the　saline　effect　on　the　pore　water　state　of　unsaturated　compacted　bentonite　at　the　microscale　is　critical　for　evaluating　the　performance　of　barrier　materials　in　nuclear　waste　geological　repositories.　In　this　paper,　the　pore　water　redistribution　and　pore　water　state　of　unsaturated　compacted　bentonite　considering　the　saline　effect　is　investigated　via　nuclear　magnetic　resonance　(NMR)　technique.　It　is　found　that,　with　increasing　pore　water　salinity,　the　pore　water　content　decreases　and　pore　water　is　distributed　in　smaller　pores,　which　is　consistent　with　the　swelling　deformation　behavior　of　bentonite　at　the　macroscale　and　the　diffuse　double　layers　(DDL)　theory　at　the　microscale.　In　addition,　the　saline　effect　on　pore　water　distribution　is　weakened　with　the　increase　in　matric　suction　due　to　the　shrinkage　deformation　of　bentonite　during　drying.　Then,　the　saline　effect　on　the　pore　water　state　of　unsaturated　compacted　bentonite　is　discussed　via　the　concept　of　effective　activation　energy.　It　is　shown　that　the　drainage　of　pore　water　and　increased　pore　water　salt　concentration　(or　the　increase　of　matric　suction　and　osmotic　suction)　both　elevate　the　effective　activation　energy　of　bentonite,　decreasing　pore　water　mobility.　The　saline　effect　on　the　permeability　coefficient　of　bentonite　is　also　discussed.　For　bentonite　under　larger　matric　suction　and　osmotic　suction　conditions,　the　permeability　coefficient　is　smaller.　©　2023　Elsevier　Ltd