A polarization maintaining optical fiber, wherein the polarization maintaining optical fiber comprises, in order from the inside to the outside, a fiber core, a quartz cladding layer, an inner coating layer and an outer coating layer; the quartz cladding layer is located at the periphery of the fiber core, two stress zones are provided between the quartz cladding layer and the fiber core, and the two stress zones are symmetrically distributed along the center of the fiber core; the fiber core comprises, in order from the inside to the outside, a circular central core region and at least one annular region concentrically arranged with the central core region, and the refractive indexes of the central core region and the annular region are different; the inner coating layer and the outer coating layer are both of a double-layer structure, the modulus of each layer of the inner coating layer and the outer coating layer is different, and the modulus from the inside to the outside increases sequentially; wherein the refractive index of the central core region is n1, the refractive index of the annular region is n2, the refractive index of the quartz cladding layer is n3, the refractive index of the central core region relative to the quartz cladding layer is △n1, and the refractive index of the annular region relative to the quartz cladding layer is △n2, and △n1<△n2, wherein the value of △n1 ranges from 0.4% to 1.3%, and the value of △n2 ranges from 0.6% to 1.5%; wherein the diameter of the central core region is d1, the outer diameter of the annular region is d2, the diameter of the stress zone is d3, the outer diameter of the quartz cladding layer is d4, and d1 <d2 <d3 <d4, wherein the value of d1 ranges from 4.0 μ m to 5.0 μ m, the value of d2 ranges from 5.0 μ m to 6.0 μ m, the value of d3 ranges from 22.0 μ m to 26.0 μ m, and the value of d4 ranges from 79.0 μ m to 81.0 μ m. the fiber core comprises, in order from the inside to the outside, a circular central core region and at least one annular region concentrically arranged with the central core region, and the refractive indexes of the central core region and the annular region are different; the inner coating layer and the outer coating layer are both of a double-layer structure, the modulus of each layer of the inner coating layer and the outer coating layer is different, and the modulus from the inside to the outside increases sequentially; wherein the refractive index of the central core region is n1, the refractive index of the annular region is n2, the refractive index of the quartz cladding layer is n3, the refractive index of the central core region relative to the quartz cladding layer is △n1, and the refractive index of the annular region relative to the quartz cladding layer is △n2, and △n1<△n2, wherein the value of △n1 ranges from 0.4% to 1.3%, and the value of △n2 ranges from 0.6% to 1.5%; wherein the diameter of the central core region is d1, the outer diameter of the annular region is d2, the diameter of the stress zone is d3, the outer diameter of the quartz cladding layer is d4, and d1 <d2 <d3 <d4, wherein the value of d1 ranges from 4.0 μ m to 5.0 μ m, the value of d2 ranges from 5.0 μ m to 6.0 μ m, the value of d3 ranges from 22.0 μ m to 26.0 μ m, and the value of d4 ranges from 79.0 μ m to 81.0 μ m.