The present invention relates to the technical field of optical communications, and relates to an optical amplification method and an amplifier, and in particular, to a self-adaptive wave band amplification method and amplifier. The present invention consists of a master amplifying unit and a salve amplifying unit, and can autonomously detect the service signal wave band range of an optical transmission line, and according to the detection result, the two amplifying units do not need to perform scheduling or configuration from the level of network management, and perform direct interaction and action from the bottom layer to implement self-adaptive on, off and adjustment in real time. On one hand, power consumption is reduced, and energy is saved; and on the other hand, the performance is optimized, and an optimal optical amplification index is obtained.