To　study　the　promotion　process　of　cement　hydration　by　polycarboxylate　superplasticizers　modified　calcium　silicate　hydrate　(C–S–H/PCE)　and　understand　the　mechanism　of　C–S–H/PCE　seeds　promotion　of　cement　hydration.　Acrylic　acid-based　polycarboxylate　superplasticizer　(PCE-1)　and　silane-based　polycarboxylate　superplasticizer　(PCE-2)　were　used　to　surface　modify　the　hydrothermal　synthesized　calcium　silicate　hydrate　(C–S–H/Unmodified)　seeds,　resulting　in　the　polycarboxylate　superplasticizer　modified　C–S–H　seeds　(C–S–H/PCE-1　and　C–S–H/PCE-2).　Subsequently,　these　three　C–S–H　seeds　were　added　to　the　cement　paste.　The　compressive　strength,　phase　composition,　and　heat　release　curve　of　cement　paste　and　the　surface　tension　of　C–S–H　seeds　were　tested.　The　results　showed　that　the　surface　modification　of　PCE-1　and　PCE-2　resulted　in　an　increase　in　the　surface　contact　angle　of　C–S–H　seeds　from　36.9°　to　41.1°　and　42.9°,　resulting　in　lattice　mismatch　of　the　sedimentary　phase　(hydration　product)　on　the　surface　of　the　substrate　material　(C–S–H　seeds)　and　inhibiting　the　epitaxial　growth　of　cement　hydration　products　on　the　surface　of　C–S–H　seeds.　PCE　modification　reduced　the　promoting　effect　of　C–S–H　seeds　on　the　hydration　process　of　Portland　cement.　Moreover,　the　degree　of　reduction　in　the　hydration　promoting　effect　of　C–S–H/PCE-2　on　Portland　cement　is　significantly　greater　than　that　of　C–S–H/PCE-1　crystal　nucleus.　Tests　of　the　adsorption　equilibrium　of　PCE　in　the　pore　solution　indicated　that　the　C–S–H/PCE　seeds　did　not　directly　introduce　new　crystal　nucleation　sites　but　exposed　new　C–S–H　surfaces　through　the　desorption　of　PCE　on　the　surface　of　C–S–H/PCE　seeds.　The　desorption　degree　of　PCE　on　the　surface　of　C–S–H/PCE　seeds　determined　the　promoting　effect　of　C–S–H/PCE　seeds　on　cement　hydration.　©　2023　Chinese　Ceramic　Society.　All　rights　reserved.