The　characristic　of　electrical　double　layer(EDL)on　the　solid⁃liquid　interface　in　alkali⁃activated　slag　cementitious　materials　were　described.　The　Zeta　potential　under　different　concentrations　of　chloride　and　surfactant　dosages　was　measured　and　analyzed.　Mechanisms　of　the　EDLs´　effect　on　chloride　diffusion　and　adsorption　were　clarified.　The　results　show　that　the　Zeta　potential　of　alkali⁃activated　slag　cementitious　materials　is　negative,and　it　becomes　less　negative　with　an　increase　in　chloride　concentration.　Cationic　surfactants　can　convert　the　Zeta　potential　to　positive　value,thereby　improving　the　capacity　of　chloride　adsorption　and　reducing　the　effective　chloride　diffusion　coefficient.　However,anionic　surfactants　have　the　opposite　effect.　The　change　of　EDLs´　effect　on　the　pore　surface　of　alkali⁃activated　slag　cementitious　materials　can　alter　the　capacity　of　chloride　adsorption　by　more　than　50%.　©　2023　Tongji　University.　All　rights　reserved.