The　wide　application　of　surfactants　in　cement-based　materials　requires　the　understanding　of　the　influence　of　surfactants　on　the　structure　and　properties　of　C-S-H　gel.　In　this　study,　cation　surfactants　(CTAB)　and　anion　surfactants　(SDS)　in　ionized　type　are　successfully　intercalated　into　C-S-H　gel,　generating　different　molecular　models　through　molecular　dynamics　simulation.　Systematic　analysis　and　quantitative　description　were　performed　on　the　molecular　structures,　bonding　properties　together　with　deformation　and　fracture　mechanisms.　It　was　found　that　the　majority　of　Br-　ionized　from　CTAB　could　interact　with　Ca_interl,　forming　Br--Ca_interl　bonds.　Smaller　Na+　ionized　from　SDS　could　bond　with　both　O_bri　and　O_nbri　atoms,　while　O-　and　O　atoms　in　SDS　anions　could　interact　with　Ca_interl　atoms　as　well.　It　is　noteworthy　that　the　intercalation　of　CTAB　into　C-S-H　gel　promotes　the　diffusion　of　water　molecules,　whereas　the　intercalation　of　SDS　into　C-S-H　gel　inhibits　the　diffusion　of　water　molecules.　Uniaxial　tensile　simulation　results　reveal　that　the　breakage　of　both　H_water-O_water　hydrogen　bonds　and　Ca_interl-O_water　bonds　dominates　the　failure　process　of　CTAB/C-S-H　gel,　while　the　breakage　of　H_water-O_water　hydrogen　bonds　governs　the　fracture　of　SDS/C-S-H　gel.　(C)　2022　American　Society　of　Civil　Engineers.