Precipitated silica was prepared with silicon tetrachloride and water glass as silica precursor, polyethylene glycol(PEG) and absolute alcohol as additives. The effects of final solution pH, reaction temperature, water glass concentration and the addition of polyethylene glycol and anhydrous ethanol on particle size of silica were investigated. At the optimal technological conditions, amorphous silica particles were prepared with average diameters of 284nm. The structure of the powders were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), Fourier transform infrared spectroscopy(FTIR), X-ray diffraction(XRD) and laser nano-particle size analyzer.