Filler is one of the most important components of paper. Silica is a kind of excellent filler for its special chemical structure. Silica was prepared in the laboratory, and applied into paper. The dispersion properties of the silica with different sizes in paper sheets, the effect of smash on dispersion property of silica in paper sheets, the effect of silica on the zeta potential of newspaper pulp system, the effect of retention agent cationic polyacrylamide on zeta potential of newspaper pulp system and the effect of silica on properties of paper sheet were measured. The results show that the fineness of the silica used in paper is the most important factor which affects the dispersion. The addition of silica and the use of retention agent cationic polyacrylamide increase the zeta potential of the newspaper pulp system. The addition of precipitated silica increases the whiteness of paper slightly and the opacity obviously.