This　study　aims　to　disclose　the　working　mechanisms　of　a　novel　shrinkage-reducing　polycarboxylate　superplasticizer　(SR-PCA)　in　mitigating　autogenous　shrinkage　of　cement　paste.　The　properties　of　pore　solutions　(-including　the　surface　tension　and　contact　angle),　ions　concentration　in　pore　solutions,　internal　relative　humidity　(RH),　dynamic　elastic　modulus,　pore　structure　characteristic　and　autogenous　shrinkage　are　thoroughly　investigated.　The　results　indicate　that　SR-PCA　substantially　reduces　the　autogenous　shrinkage　of　cement　paste.　From　the　perspective　of　pore　solution　properties,　SR-PCA　increases　the　hydrophobicity　of　the　pore　solution　and　reduces　the　surface　tension,　thus　lowering　the　internal　RH　depression,　capillary　stress　development　and　autogenous　shrinkage　of　the　cement　paste.　Also,　SR-PCA　reduces　the　volume　fraction　of　mesopore　(pore　size　less　than　50 nm)　where　the　capillary　stress　is　exerted,　thereby　lowering　autogenous　shrinkage.　Moreover,　the　presence　of　SR-PCA　increases　the　expansion　stress　mainly　induced　by　portlandite,　reduces　the　capillary　stress　and　enhances　the　dynamic　elastic　modulus　of　cement　pastes,　contributing　to　controlling　autogenous　shrinkage.　©　2022,　The　Author(s).