The present application provides a wavelength configuration method for a multi-wavelength passive optical network, which includes: scanning, by an ONU, a downstream receiving wavelength, and receiving, downstream wavelength information of each downstream wavelength channel that is broadcast by an OLT separately through each downstream wavelength channel of a multi-wavelength PON system; establishing, by the ONU, a downstream receiving wavelength mapping table, where an entry of the downstream receiving wavelength mapping table includes downstream receiving wavelength information, drive current information of a downstream optical receiver and receiving optical physical parameter information of the ONU; selecting, by the ONU, one downstream wavelength from the downstream wavelength information broadcast by the OLT, and setting, according to the drive current information of the downstream optical receiver recorded in a related entry of the downstream receiving wavelength mapping table, an operating wavelength of the downstream optical receiver to the selected downstream wavelength.