IMPS(intensity-modulated photocurrent spectroscopy) and IMVS(intensity–modulated photovoltage spectroscopy) measurements are utilized to analyse different mechanisms for enhancing the performance of dye-sensitized solar cells(DSC) based on modified anode. Electron transport and back reaction in DSC are investigated under different illumination intensities. The modifications of anode, blocking layer and modified TiO2films, are performed by electrodeposition. It is found that short-current density Jsc and efficiency η of DSC are improved, but different mechanisms are obtained: the optimization of TCO by coating a blocking layer can effectively extend electron lifetime τ n, but it has little influence on electron transport. On the other hand, the optimization of TiO2 film can enhance electron transport, finally shorten transit time τ d and extend τ n.