Abstract: Improving the dispersion of silica is in favor of enhancing the reinforcement effect of silica for tire rubber,increasing the tensile strength and decreasing the rolling resistance of tire rubber.In this paper,the influence of process parameters on the dispersion of silica during the wet grinding was studied by orthogonal experiments.Range analysis results show that the zirconium ball diameter has the largest effect on the dispersion of silica.Silica disperses best under the conditions:5 000 r/min of the rotation rate,80 min of milling time,0.9 mm of zirconium ball diameter,20 g of the mass of silica and 2% of sodium hexametaphosphate(SHMP).Silica's median particle diameter(D50) decreases to 112 nm.