Highly dispersed ZnO nanosol, having an average particle size of about 40nm based on Particle Size Analysis (PSA), was prepared under aqueous solution without the removal of large particles by centrifugation. The ZnO nanosol was investigated on the effect of various dispersion parameters, i.e. milling time, dispersant content, pH, etc. The nanosol was effectively dispersed at 20~30 wt% of dispersant amount compared to ZnO content under ball-milling for 10 hours at pH 10. The dispersion characteristic of the nanosol was investigated into particle size and zeta potential. We discussed on the dispersion behavior of (-) charged ZnO particle surrounded by dispersant together with the variation of (-) charged dispersant's amount in aqueous medium at pH 10. The ZnO powder and nanosol were characterized by SEM, TEM, TGA, FT-IR, PSA and Zeta-potential.