Abstract: The effect of some chemical retarders,often used for alkali activated cement such as Pb(NO₃)₂,Zn(NO₃)₂, and NaCl etc.,on the gelation time of alkali-activated carbonatite slag cementitious material (AACSCM) was investigated. The results are as follows: Pb(NO₃)₂ or Zn(NO₃)₂ has retarding effect when its addition is not less than 3% of blast furnace slag, and for NaCl or Na₂B₇O₄ the addition should not be less than 8%; chemical reagent BS can efficiently retard the gelation of AACSCM paste and improve the strength of AACSCM mortars. In addition, the fluidity of AACSCM paste can be kept constantly for 4 hours. The retarding effect of BS is mainly attributed to the formation of a protective layer on the surface of slag grain due to the reaction between BS and water glass.