Abstract: The hydration products and microstructure of slag cementing materials were characterized and the influence of slag cementing materials on the consolidation of tailings was investigated by using X-ray diffraction analysis, scanning electron microscopy and thermogravimetry-differential scanning calorimetry analysis. Microscopic experimental results indicate that the main hydration products of slag cementing materials are calcium silicate hydrate gel (C-S-H), ettringite (AFt), a small amount of partheite (Ca₂Al₄Si₄O₁₅(OH)₂·4H₂O) and zeolite minerals. It is found that the crystal structure recombines and rearranges in the hydration process with the increase of curing time. Cristobalite, mica and carbonate minerals (calcite, dolomite, etc.) are active components in the tailing consolidation process, which can generate new crystal and gelatinous minerals. This is the main reason for the difference of consolidation microstructure.