To achieve effective cementation of fine tailings, slag-based binders were prepared using Portland cement clinker stimulation, early strength activator (ESA, mixture of anhydrite and triethanolamine at 97:3 (w/w)) activation and slag pulverization methods. The compressive strength, hydration products, slag reaction degree and non-evaporable water content of the consolidated samples under different curing times were analyzed to clarify the application performance and early strength action mechanisms of this slag-based binder. The results showed that clinker alone was able to effectively stimulate the slag's cementitious property, but the cementation strength was relatively low. The addition of ESA in the clinker activated slag promoted the conversion of C(4)AH(13) into ettringite (AFt) and accelerated the consumption of Ca(OH)(2), all of which significantly improved the early cementation strength of fine tailings. Slag pulverization promoted the slag reaction degree and increased the yield of hydrated products, which led to a further increase in the early strength of the slag-based binder. Eventually, a more efficient and higher early strength slag-based binder was prepared with the composition of 27% clinker, 10% ESA and 63% pulverized slag, and the cementation strength at 3 curing days for the fine tailings sample was 231% more than that of P.O 42.5 Portland cement.