A split-type photoelectrochemical（PEC）method was developed for the detection of Escherichia coli O157∶H7（E.coli O157∶H7）with antibacterial peptide as a recognizer.Firstly,water soluble thioglycolic acid capped lead selenide quantum dots（PbSe QDs）were synthesized by a simple water bath method,then PbSe QDs were assembled on surface of indium tin oxide（ITO）electrode through electrostatic interaction,and the Pb2+ on surface of PbSe QDs could be exchanged with Zn2+ to form a ZnSe/PbSe/ZnSe quantum well（QW）,which could promote the electron-hole separation and improve the cathode photocurrent on the ITO/PbSe electrode.This method avoided the immobilized biomolecules on the electrodes to retard the PEC signal,and showed a highly efficient detection.The detection range of the method for E.coli O157∶H7 ranged from 10.0 CFU/mL to 5.0×106 CFU/mL with a detection limit of 4.0 CFU/mL.The recoveries varied from 94.7% to 104% with relative standard deviations of 1.9%-2.8%.