Abstract: In this work, a visible light-responsive photoelectrochemical (PEC) sensor based on PPy/Cu2O molecular imprinting composite film for microcystin-LR (MC-LR) has been fabricated. Uniformed Cu2O nanoparticles were electrodeposited on the pretreated indium doped tin oxide-coated glass (ITO) by elaborately controlling the deposition process, and were used as photocatalyst to produce photocurrent under visible light. Subsequently, molecularly imprinted polypyrrole (PPy) was modified on the surface of Cu2O/ITO electrode by electropolymerization process, which would create a certain amount of special recognition sites to enhance the ability of selectivity to MC-LR. The PEC molecular imprinting sensors were used for rapidly analyzing the MC-LR concentration by recording the change of photocurrent density. Results showed that the change of photocurrent density was linearly proportional to the logarithm of the MC-LR concentration over the range of 1.0 ng L-1 to 100 ng L-1 and 100 ng L-1 to 10.0 μg L-1 with the low detection limit of 0.23 ng L-1 (S/N=3). Meanwhile, the PEC sensors exhibited specific selectivity to MC-LR through exposed to a certain concentration of interfering solutions. The constructed PEC sensors demonstrated the good applicability in local water systems, suggesting that the promising application of integrating PEC and molecular imprinting technology could be applied to detect other contaminants of emerging concern