This　study　aims　to　investigate　the　effect　mechanism　of　slag　activity　on　the　basic　tensile　creep　of　alkali-activated　slag　mortar　(AM)　using　a　combined　activator　of　quicklime　and　sodium　carbonate　(molar　ratio　1:1).　Based　on　the　results　of　setting　time,　compressive　strength,　dynamic　modulus,　autogenous　shrinkage,　basic　tensile　creep　and　microstructure,　the　basic　tensile　creep　mechanism　of　AM　with　different　activity　slag　is　discussed.　Results　indicate　that　as　slag　activity　increases,　the　degree　of　hydration　increases　and　more　C-A-S-H　gel　generates;　meanwhile,　the　nominal　crystal　-binder　ratio　decreases,　resulting　in　a　high　autogenous　shrinkage　of　AM.　Autogenous　shrinkage　is　the　driving　force　of　the　basic　tensile　creep.　The　increased　amount　of　Q2(1Al)　results　that　more　Na+　is　absorbed　by　C-A-S-H　gel,　which　promotes　the　slippage　of　C-A-S-H　gel.　Moreover,　the　collapsing　of　C-A-S-H　gel　is　easier　with　its　shorter　mean　chain　length　(MCL).　Therefore,　the　basic　tensile　creep　increases　as　slag　activity　increases.　Because　of　the　higher　autogenous　shrinkage,　smaller　nominal　crystal-binder　ratio　and　larger　amount　of　Q2(1Al),　AM　has　larger　basic　tensile　creep　than　ordinary　Portland　cement　mortar　(OM).