An embodiment of the present invention discloses a method of performing target Raman gain locking and a Raman fiber amplifier. The Raman fiber amplifier comprises a coupler (1) and a control unit (15), wherein the control unit comprises a target gain locking module. A detection circuit formed by filters and optical power detectors is connected between an output side of the coupler (1) and an input side of the control unit (15). Said method uses the control unit (15) to adjust power of the pump laser, making the detected out-of-band ASE power value reach target out-of-band ASE optical signal power value. Thus, the target amplification gain locking can be realized. Optical path according to embodiments of the present invention has a simple structure. The Raman gain can be configured flexibly according to line condition, and automatic control and locking of gain of the Raman fiber amplifier can be realized.