To improve the dispersion stability and flowability of a coal-water slurry by using a dispersion stabilizer comprising a specific sulfonated polymer and an acrylate polymer.

This dispersion stabilizer comprises 99-30wt.% arom. polymer selected from among a condensate of formalin with a sulfonated arom. compd., salt thereof, and a polymer having a styrenesulfonic acid backbone and 1-70wt.% acrylate polymer selected from among a dialkyl phosphinate polymer represented by formula I, a monoalkyl phosphinate polymer represented by formula II, and a monoalkyl phosphonate polymer represented by formula III. In those formulas M2 is H, Na, K, NH4 or Li; 'polymer' in those formulas is represented by formula IV; R' is H, methyl, or ethyl; Z2 is represented by formula V; and (n) is 5-100,000. This stabilizer is incorporated in an amt. of 0.05-2.0wt.% (based on coal solid) into a coal-water slurry comprising 50-80wt.% coal and 50-20wt.% water.