The seed particle growth technique was developed to achieve the mono-dispersed large silica particles (about 2 m) by controlling the particle growth and primary particle nucleation processes in sol-precipitation. Using the salt additive of KCl, the mono-modal distribution of particles could be achieved because KCl enhanced the seed particle growth by charge neutralization and impressed the secondary particle formation. At KCl concentration of 10(-2) mol/l, the seed particles were monotonically enlarged without a secondary particle formation, as increasing the TEOS concentration to 0.2 mol/l. Further increasing the TEOS concentration resulted in the bi-modal distribution of the product particles due to the secondary particle formation. Also, the amount of seed particles influenced on the particle size and distribution because the particle growth rate and the secondary particle formation were changed. In addition, it was observed that the mono-modal particles of about 2000 nm were produced by multi step growth technique of the seed particles.