A method for controlling an optical network unit, characterized by comprising: an optical line terminal setting a protection wavelength channel for a target optical network unit, and reserving a corresponding network resource for the target optical network unit on the protection wavelength channel (S201), wherein an optical network unit with a priority higher than a certain priority threshold is set as the target optical network unit by the optical line terminal; and the optical line terminal sending information about the protection wavelength channel to the target optical network unit (S203) after the target optical network unit is registered to be online (S202), wherein the target optical network unit performs switching on the protection wavelength channel when there is a need for switching wavelength channel (S204), wherein the step of the optical line terminal setting the protection wavelength channel for the target optical network unit comprises: the optical line terminal selecting one wavelength channel from a plurality of wavelength channels of the optical line terminal, and when judging that current remaining network resources of the wavelength channel satisfy a demand of the target optical network unit, selecting the wavelength channel as a protection wavelength channel; otherwise, the optical line terminal selecting a next wavelength channel for the judgment, or the optical line terminal making the judgment again after kicking off at least one online non-target optical network unit from the wavelength channel or switching at least one online non-target optical network unit on the wavelength channel to other wavelength channels. an optical line terminal setting a protection wavelength channel for a target optical network unit, and reserving a corresponding network resource for the target optical network unit on the protection wavelength channel (S201), wherein an optical network unit with a priority higher than a certain priority threshold is set as the target optical network unit by the optical line terminal; and the optical line terminal sending information about the protection wavelength channel to the target optical network unit (S203) after the target optical network unit is registered to be online (S202), wherein the target optical network unit performs switching on the protection wavelength channel when there is a need for switching wavelength channel (S204), wherein the step of the optical line terminal setting the protection wavelength channel for the target optical network unit comprises: the optical line terminal selecting one wavelength channel from a plurality of wavelength channels of the optical line terminal, and when judging that current remaining network resources of the wavelength channel satisfy a demand of the target optical network unit, selecting the wavelength channel as a protection wavelength channel; otherwise, the optical line terminal selecting a next wavelength channel for the judgment, or the optical line terminal making the judgment again after kicking off at least one online non-target optical network unit from the wavelength channel or switching at least one online non-target optical network unit on the wavelength channel to other wavelength channels. <EOS>