In this paper, the sub-micro silica particles were prepared successfully by sol-gel method. The ammonia was introduced as a catalyst and silane coupling agent as surfactant. The impact of reaction temperature, ethyl orthosilicate (TEOS) concentration, the amount of silane coupling agent and the order added to the solution on the size of particles were investigated. The sub-micro SiO 2 particles were determined by SEM. The result showed that the average size of particles changed from 200nm to

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... nm while the reaction temperature was from 20℃ to 50℃, concentration of TEOS was 0.2mol/L to 0.3mol/L and 0.075 to 0.125ml dispersant was added after reaction. At room temperature, the silica particles grew up more easily on the condition that the concentration of TEOS was 0.3 mol/L and added 0.075 to 0.125ml dispersant after the reaction, the sub-micro silica particles with the average size of 600nm were prepared.