Using NaOH， waterglass and a mixture of NaOH and Na₂CO₃ as activators， changes of setting time and 7 d compressive strength for four kinds of binding systems including alkali activated slag， fly ash， slag/fly ash and slag/cement were studied systematically， and the fitting formulas for the changes in setting time and the prediction of early age compressive strength were obtained. The results show that under the condition of single NaOH or waterglass activating slag， adding a small amount of fly ash or cement has no significant effect on the setting time， but will reduce the compressive strength at early age. NaOH/Na₂CO₃ compound activator can effectively prolong the setting time and improve the compressive strength to a certain extent. In addition， the setting time and compressive strength of slag/cement system activated by NaOH do not increase but decrease due to the addition of Na₂CO₃. The mechanism of the effect of NaOH/Na₂CO₃ compound activator is discussed.