•Cu2O under AM1.5 illumination can promote the corrosion of Cu matrix.•The photoinduced corrosion of Cu aroused by Cu2O is detected by SVET.•A method for in-situ determining the photoinduced current is proposed. The electrochemical associated with photoelectrochemical behaviors of Cu electrodeposited with Cu2O layer were investigated in this work. The corrosion of Cu was promoted due to the enhanced anodic and cathodic processes under AM 1.5illumination compared with that in the darkness, especially for the anodic process. The photoinduced corrosion of Cu by Cu2O was detected by Scanning Vibrating Electro Technique (SVET). The effect of Cu2O on the promotion of Cu corrosion under illumination can be ascribed to the narrowed depletion layer in Cu2O under illumination, which facilitates the separation of hole-electron pairs. The resultant holes give rise to the oxidation of the Cu matrix and lead to a promoted corrosion consequently. Besides, a method for in-situ determining the photoinduced current of a semiconductor material is proposed.