In this work, photoelectrocatalytic degradation of wastewater containing methylene blue (MB) was investigated using a novel photoelectrochemical reactor – a three dimensional electrodes-photocatalytic oxidation reactor in which nano TiO2 was used as photocatalyst. The experimental results are assessed in the terms of decolorization and Chemical Oxygen Demanded (COD) removal efficiencies. The experimental results showed that the three dimensional electrodephotocatalytic reactor could effectively destroy MB within a reaction time of 30 min. It was found that the three dimensional electrode technologies under high potential bias have an apparent enhancement effect on the photocatalytic degradation of MB in water with nanometer TiO2 . At a cell voltage of 60.0 V and a concentration of 5 g·l-1 TiO2 , the decolorization and the COD removal efficiencies in the photoelectrochemical process were increased by 21.8% and 14.1%, respectively, compared to those in the single photocatalytic process.