The invention discloses an optical fiber with a ring-shaped doped layer, which is used in an optical fiber laser and composed of an inner clad layer (101), a ring-shaped doped layer (102), a middle clad layer (103), an outer clad layer (104) and a protective layer (105), wherein the ring doped layer (102), the middle clad layer (103), the outer clad layer (104) and the protective layer (105) are, from inside to outside, sequentially clad on the inner clad layer (101), and the inner clad layer (101) is an undoped optical fire core. The invention also discloses a method for preparing the optical fiber with a ring-shaped doped layer, and a laser taking the optical fiber with a ring-shaped doped layer as a gain medium. According to the invention, the traditional fiber core doping is changed into a ring-shaped doped layer, so that the laser oscillation is actually performed in a ring-shaped waveguide, and then through reasonably designing the thickness of the ring-shaped waveguide, a single-mode operation can be kept; meanwhile, because the cross section area of the doped layer is large, the optical fiber with a ring-shaped doped layer is suitable to high-power output, therefore, the output power of the optical fiber laser using the optical fiber can be improved.