TiO₂ sol is prepared by the sol-gel method using Dimethylacetamide(DMAC) as a impregnant,tetrabutyltitanate(TBT) as a precursor and acetic acid as a stabilizer.And the effect ingredients have been investigated including the way of adding water,mole ratio of water to TBT,volume ratio of DMAC to TBT,pH value and temperature.It suggests that the TiO₂ sol obtained is stable and lucid which can be used as a additive to prepare polymer and nanometer TiO₂ composite membrane,if the way of adding water dispersedly is adopted and when temperature is between 25 to 35℃,the volume ratio of DMAC to TBT is 3.5:1,the mole ratio of water to TBT range from 2 to 3,the value of pH is between 2 to 4.