The invention provides a wavelength configuration method and device and an optical module, and belongs to the field of optical communication. The method comprises steps of loading the wavelength configuration instruction into the emergent light in a low-frequency modulation signal mode; receiving returned setting information, wherein the setting information is used for checking whether the wavelength configuration instruction is accurately implemented or not; when the returned setting information is inaccurate, sending out a wavelength configuration instruction again; therefore, the communication with the receiving end optical module through the low-frequency optical signal is realized; the configuration of the light emitting wavelength of the receiving end optical module is indicated, andwhen the wavelength of the receiving end optical module is not correctly configured, the configuration of the light emitting wavelength of the receiving end optical module is indicated again, so thatthe wavelength configuration of the receiving end optical module is controlled by using the transmitting end optical module on the premise of not influencing the normal transmission of data by establishing the communication mechanism.