Doping induced visible-light adsorption is often considered as the main reason for the enhanced photocatalytic activity of TiO2. However, this work provides a new understanding on the effect of doping on the photocatalytic activity of TiO2. The investigation on the C-F codoped anatase TiO2{0 0 1} surface reveals that the impurity C and F atoms prefer to substitute for the outmost O atoms in the TiO2{0 0 1} surface rather than those in the bulk TiO2. The exhibited vectorial doping of C and F atoms in TiO2{0 0 1} surface produces a conducting layer with low electric resistance, which can promote the charge transfer in the photocatalytic reaction. This effectively inhibits the undesirable bulk recombination of photogenerated electron and hole. Hence, the optimized charge transfer in the C-F codoped TiO2{0 0 1} surface makes a great contribution to the enhanced photocatalytic activity of TiO2. Further, the surface doping treatment is a potential method to improve the performance of photocatalyst.