We present a novel all oxides semiconductor WO3/Cu2O heterojunction photoelectrode applied in photoelectrochemical water splitting. Different amount of Cu2O was loaded onto WO3 NRs by controlling the electrodeposition time and the amount influence on the photoelectrocatalytic activity of the different samples has been researched. This all oxides structure exhibits a remarkably high photoelectrocatalytic performance with a significant improved photocurrent density of 1.37 mA cm(-2) was measured at a bias voltage of 0.8 V vs RHE, which was about 3.51 times higher than that of pristine WO3 NRs. This amazing PEC performance due to the broader light absorption spectrum, the enhanced photogenerated charge carriers transfer efficiency and the suppressive electron-hole recombination rate. The research results can demonstrate a promising way for designing all oxide semiconductor heterojunction structure so that it can improve photoelectrocatalytic efficiency. Moreover, these results also suggest that the WO3 NRs/Cu2O arrays heterojunction structure has a great potential application for efficient PEC water splitting devices. (C) 2016 Elsevier B.V. All rights reserved.