The　use　of　Na2CO3　in　alkali-activated　system　(AAS)　has　attracted　an　increased　interest　since　it　provides　a　suitable　setting　time,　suitable　mechanical　properties　and　lower　cost.　However,　the　tensile　creep　behavior　of　Na2CO3activated　AAS　remains　unknown,　which　is　crucial　for　controlling　its　early　cracking.　Therefore,　this　study　aims　to　investigate　the　effect　of　Na2CO3　on　the　tensile　creep　of　slag-fly　ash　systems　activated　with　Na2SiO3　(ASF).　The　total　Na2O　equivalent　(Na2O　of　hybrid　activators/binder,　by　mass)　was　maintained　at　6%.　Various　Na2CO3　contents　(i.e.　the　ratio　of　Na2O　equivalent　of　Na2CO3　to　total　Na2O　equivalent)　were　used　in　this　paper,　namely,　0,　1/3,　1/2　and　2/3.　The　compressive　strength,　flexural　strength,　elastic　modulus,　internal　relative　humidity,　autogenous　shrinkage,　tensile　creep　and　microstructures　(X-ray　diffraction,　thermogravimetry,　mercury　intrusion　porosimetry,　scanning　electronic　microscopy-energy　dispersive　spectroscopy　and　nanoindentation)　were　investigated　for　the　ASF　system.　Results　indicate　that　the　tensile　creep　of　ASF　mortar　(ASFm)　firstly　increases　and　then　decreases　as　the　Na2CO3　contents　increases.　ASFm　with　Na2CO3　content　of　1/2　has　the　highest　tensile　creep,　which　is　236.3%　higher　than　that　of　ASFm　without　Na2CO3.　When　the　Na2CO3　content　increases　from　0　to　1/2,　Na2CO3　promots　C(N)-A-S-H　gel　formation,　increases　the　autogenous　shrinkage　and　decreases　the　contact　creep　modulus　of　gels,　leading　to　the　increases　of　the　tensile　creep　of　ASFm.　However,　excessive　Na2CO3　(content＞1/　2)　reacts　preferentially　with　Ca　ion　dissolved　from　slag　to　generate　CaCO3,　inhibiting　the　gel　formation.　Moreover,　CaCO3　plays　a　role　in　limiting　the　gel　deformation,　which　remarkably　reduces　autogenous　shrinkage　and　increases　the　contact　creep　modulus　of　gels,　and　therefore　the　tensile　creep　of　ASFm　is　reduced.