The kinetics of photocatalysis can be us ually described by Langmiur-H inshelwood adsorption expression. The adsorption can be greatly influenced by the surface properties of photocatalyst. Triple layer model (TLM) was chosen to describe the surface adsorption of TiO2 based on electrical double layer (EDL) theory at the TiO2/water interface. And through the potentiometrictit ration the parameters of TLM were determined by the extrapolation method and Fit eql3.1 software. The results show that surface complexation dominates the surfac e charge and the numerical calculation fits the experiment data satisfactorily.