This study deals with the effectiveness and its reaction of stearic acid, ethyl silicate and ethylene glycol as grinding aids in grinding of Hwasun flint clay by dry ball milling process. Results are follows ; 1) It was effective that stearic acid and ethyl silicate act as the grinding aids in grinding of Hwasun flint clay. Also, it was proven that addition of stearic acid and ethyl silicate was the most effective in 1.0 and 0.75wt%, respectively. 2) The addition of ethylene glycol below 0.5wt% showed better result than none, but when added more than 0.5wt% it behaved as the inhibitor of grinding process. 3) It was investigated that grinding aids increased the ability of the particle dispression by reducing the strong chhesive forces which is caused by extensive surface tension of water.