The feasibility of substituting alcohol fermentation wastewater of maize and cassava for water to prepare coal slurries was explored. The rheological and stability properties of coal alcohol fermentation wastewater slurries were studied and compared with that of coal water slurry. The results showed that both coal maize and cassava alcohol fermentation wastewater slurries exhibited shear-thinning behavior. Because of the oxygen-containing functional groups (carboxylic) with exchangeable cations in alcohol fermentation wastewater and its low pH value, coal maize and cassava alcohol fermentation wastewater slurries exhibited the higher apparent viscosities, the stronger shear-thinning behavior, and worse stabilities compared with the coal water slurry. In addition, alcohol fermentation wastewater should be diluted for preparing coal slurries to meet industrial need in apparent viscosity and solid concentration at the same time.