Abstract: Monodispersed micrometer SiO<SUB>2</SUB> microspheres were synthesized by two-phase sol-gel method,using tetraethylortho silicate,ammonia,ethanol,water,and micro-electrolyte as raw materials.Effects of electrolyte concentration,feeding time and ways of precursor solutions as well as mixed ratio of different solvents on the diameter and particle size distribution of SiO<SUB>2</SUB> microspheres were studied.Results indicated that the diameter of SiO<SUB>2</SUB> microspheres decreased at first and then increased,with the increase of electrolyte concentration.The diameter of SiO<SUB>2</SUB>microspheres increased gradually with the extension of feeding time of precursor solutions.SiO<SUB>2</SUB> microspheres synthesized by continuous feeding way had better monodispersity than that synthesized by intermittent feeding way.The kinds of solvent had significant influence on the diameter and particle size distribution of SiO<SUB>2</SUB> microspheres.The diameter of SiO<SUB>2</SUB> microspheres could be controlled by adjusting the mixed ratio of different solvents and SiO<SUB>2</SUB> microspheres with better monodispersity could be prepared finally.