The invention belongs to the optical and laser optoelectronic technology field and particularly relates to an erbium-doped polarization maintaining fiber. The erbium-doped polarization maintaining fiber comprises a fiber core, an inner cladding layer, an outer cladding layer and stress layers, wherein the fiber core is arranged at the center of the inner cladding layer, is yttrium, aluminum, phosphorus co-doped silica and has the maximum refractive index delta percentage delta1, the inner cladding layer is the silica and has the maximum refractive index delta percentage delta2, the stress layers are symmetrically spaced on both sides of the fiber core and arranged in the inner cladding layer, are boron-doped silica and have the maximum refractive index delta percentage delta3, the outer cladding layer is arranged around periphery of the inner cladding layer and has the maximum refractive index delta percentage delta4, the delta1 is greater than the delta2, the delta2 is greater than the delta3, the delta3 is greater than the delta4, and the distribution volume V3 is greater than 3460%deltaum<2> and is smaller than 6060%deltaum<2>.