Abstract: Silica microspheres were prepared by sol-gel processing of tetraethylorthosilicate （TEOS） in ethanol-ammonia aqueous solution containing different kinds of water soluble polymers.Effects of kinds of polymers，such as homopolymer poly（vinyl pyrrolidone） （PVP） and block copolymers poly（ethylene oxide）-poly（propylene oxide）-poly（ethylene oxide） with different molecular weights and length of chain segment （i.e.P123，P104，F108，F127） on components and size of silica mi-crospheres were investigated and characterized by the measurements of thermogravimetry（TG），nanoparticle tracking analy-sis（NTA），and scanning electron microscopy（SEM）.Results showed that water soluble polymers were not in the micro-spheres，but that affected the particle size and distribution.The particle size decreased apparently by increasing the amount of P123.The size of microsphere prepared using 0.6 g of P123（other conditions：ammonia of 18.0 g，ethanol of 30.0 g，and TEOS  of 2.0 mL） was 293 nm，much smaller than 529 nm in size of particle in free P123 case.

Key words: silica, size control, macromolecule