The invention relates to the technical field of optical fiber amplifiers, and specifically relates to a polarization-maintaining rare earth doped optical fiber amplifier that comprises a case; a plurality of strip-shaped through holes which are distributed at equal intervals are formed in the top, close to the edge of the front side, of the case; a dustproof device is arranged at the top of the case and located over the strip-shaped through hole, the dustproof device comprises a mounting bin, a U-shaped fixing plate is arranged in the mounting bin, first primary filter cotton is arranged betwe...
