PURPOSE: To obtain an aqueous polyether sulfone dispersion which enables smooth of the surface of coating films, by dividing under high shearing force an aqueous dispersion yielded by mixing a polyether sulfone powder with water and adding a polar org. solvent to the mixture.

CONSTITUTION: A polar org. solvent is added to a mixture of a polyether sulfone powder and water to obtain an aqueous dispersion. Said dispersion is divided by exerting high shearing force to yield an aqueous polyether sulfone dispersion. In order that the surface of coating films of the aqueous polyether sulfone dispersion is smooth, the particle size of said polyether sulfone is pref. 5μ or below, particularly about 2W3μ. Preferable polar org. solvents include N-methyl-2- pyrrolidone, N,N-dimethylformamide and N,N-dimethylacetamide. The compsn. of said dispersion is pref. 5W35wt% polyether sulfone, 15W55wt% water, and 35W65wt% solvent.