The present invention relates to the technical field of optical communications, and particularly relates to a wavelength locking optical module, a device, and a wavelength locking method. The optical module comprises a DSP unit, a TOSA, and a ROSA. The DSP unit has a signal output terminal connected to the TOSA and a signal input terminal connected to the ROSA. A TEC is provided within the TOSA, and is used to adjust a temperature according to a control signal sent from the DSP unit and accordingly adjust a emission wavelength of the TOSA. An optical filter is provided within the ROSA and used to filter a wave, such that light having a pre-determined wavelength passes through the filter and is converted into an electrical signal and output to the DSP unit. The DSP unit calculates an optical power according to the received electrical signal, and determines wavelength control of the TOSA according to an optical power change. The present invention has the optical filter provided within the ROSA, combines an original optical detection capability of the ROSA and a signal processing capability of the DSP unit to monitor a wavelength change, and adjusts a wavelength by means of the TEC, thereby reducing TOSA volume, simplifying processes and reducing costs.