n　recent　years,several　nanoparticles　have　been　studied　as　potential　nucleation　seeds　for　cement　hydration.　Synthetic　nano-calcium　silicate　hydrate　(C-S-H),nano-SiO2,nano-CaCO3,nano-TiO2,and　carbon　nanotubes　are　investigated　to　determine　their　abilities　to　reduce　the　nucleation　barrier　by　providing　nucleation　sites　for　hydration　products,thereby　accelerating　cement　hydration.　Among　them,the　nano　C-S-H　seeds　are　found　to　be　a　good　nucleation　substrate　for　C-S-H　gel,and　provided　the　most　significant　cement-hydration　acceleration.　Thus,nano　C-S-H　seeds　are　attracting　increasing　attention　from　both　academia　and　industry.　To　date,methods　of　synthesizing　nano　C-S-H　seeds,as　well　as　the　seed　nucleation　process　and　mechanism　of　cement　hydration,have　all　been　studied.　In　many　studies,the　nano　C-S-H　suspension　is　prepared　by　co-precipitating　in　the　presence　of　polymer　that　exhibited　nanoscale-sized　grains　and　good　dispersion　stability　which　followed　a　non-classical　nucleation　mode.　After　applying　it　to　cement,nano　C-S-H　seeds,with　a　high　surface　area,acted　as　additional　nucleation　sites　for　C-S-H　gel,which　reduced　the　nucleation　barrier　of　the　C-S-H　gel.　Thus,the　nano　C-S-H　seeds　effectively　accelerated　the　cement　hydration　rate.　The　nano　C-S-H　seeds　also　enhanced　the　early　strength　development　of　the　cement,　particularly　within　the　first　day　of　aging.　In　contrast　to　traditional　cement　accelerators,nano　C-S-H　seeds　have　the　advantages　of　low　dosing　requirements,good　effect　on　early　strength,and　no　impact　on　cement　and　concrete　durability.　To　a　certain　extent,these　seeds　also　compensate　for　the　slow　early-strength　growth　of　supplementary　cementitious　materials(SCMs).　Therefore,nano　C-S-H　seeds　have　promising　applications　in　low-temperature　and　slipform　construction,the　production　of　precast-concrete　products,and　other　projects　that　require　high　levels　of　early　strength.　Nano　C-S-H　seeds　have　the　potential　to　become　a　widely　used　hydration　accelerator　for　cement　and　concrete.　In　this　review,many　studies　about　nano　C-S-H　seeds　are　analyzed　and　summarized.　Including　the　methods　for　synthesizing　C-S-H　seeds,as　well　their　nucleation　process,mechanism　of　interaction　with　polymers,and　effects　on　the　cement-hydration　process.　Based　on　theoretical　principles　and　experimental　results,current　shortcomings　are　evaluated,and　the　problems　that　still　need　to　be　addressed　are　identified.　This　review　provides　a　theoretical　basis　and　future　direction　for　scientific　research　and　engineering　applications　of　nano　C-S-H　seeds.　©　2023　Cailiao　Daobaoshe/　Materials　Review.　All　rights　reserved.