A doping optimized single-mode optical fiber with ultralow attenuation, comprising: a core layer and cladding layers, wherein the cladding layers comprise an inner cladding layer surrounding the core layer, a trench cladding layer surrounding the inner cladding layer, an auxiliary outer cladding layer surrounding the trench cladding layer, and an outer cladding layer surrounding the auxiliary outer cladding layer; wherein the relative refractive index Δn 1 of the core layer is in a range of -0.08% to 0.12%; wherein the relative refractive index Δn 2 of the inner cladding layer is in a range of -0.35% to -0.14%; wherein the relative refractive index Δn 3 of the trench cladding layer is in a range of -0.75% to -0.25%; and wherein the relative refractive index Δn 4 of the auxiliary outer cladding layer is in a range of -0.56% to -0.14%; the core layer is a germanium and fluorine co-doped core layer, and a relative refractive index contribution Δ Ge of germanium in the core layer is less than or equal to 0.12%; wherein a radius r 1 of the core layer is in a range of 4.0 μm to 6.0 μm, wherein a radius r 2 of the inner cladding layer is in a range of 10 μm to 14 μm, wherein a radius r 3 of the trench cladding layer is in a range of 12.5 μm to 17 μm, and wherein a radius r 4 of the auxiliary outer cladding layer is in a range of 40 μm to 50 μm, characterized in that a content of fluorine in the core layer is less than or equal to 0.5 wt%, wherein a content of fluorine in the inner cladding layer is in a range of 0.5 wt% to 1.5 wt%, wherein a content of fluorine in the trench cladding layer is in a range of 1 wt% to 3 wt%, wherein a content of fluorine in the auxiliary outer cladding layer is in a range of 0.5 wt% to 2 wt%, wherein the outer cladding layer is a metal-doped silicon dioxide glass layer, wherein metal dopants doped in the outer cladding layer comprise aluminum and alkali metals, which are one or more of lithium, sodium and potassium, and a total content of the metal dopants is less than or equal to 25 ppm, wherein a content of aluminum is in a range of 1 ppm to 18 ppm, and a total content of the alkali metals is less than or equal to 2 ppm. a core layer and cladding layers, wherein the cladding layers comprise an inner cladding layer surrounding the core layer, a trench cladding layer surrounding the inner cladding layer, an auxiliary outer cladding layer surrounding the trench cladding layer, and an outer cladding layer surrounding the auxiliary outer cladding layer; wherein the relative refractive index Δn 1 of the core layer is in a range of -0.08% to 0.12%; wherein the relative refractive index Δn 2 of the inner cladding layer is in a range of -0.35% to -0.14%; wherein the relative refractive index Δn 3 of the trench cladding layer is in a range of -0.75% to -0.25%; and wherein the relative refractive index Δn 4 of the auxiliary outer cladding layer is in a range of -0.56% to -0.14%; the core layer is a germanium and fluorine co-doped core layer, and a relative refractive index contribution Δ Ge of germanium in the core layer is less than or equal to 0.12%; wherein a radius r 1 of the core layer is in a range of 4.0 μm to 6.0 μm, wherein a radius r 2 of the inner cladding layer is in a range of 10 μm to 14 μm, wherein a radius r 3 of the trench cladding layer is in a range of 12.5 μm to 17 μm, and wherein a radius r 4 of the auxiliary outer cladding layer is in a range of 40 μm to 50 μm, characterized in that a content of fluorine in the core layer is less than or equal to 0.5 wt%, wherein a content of fluorine in the inner cladding layer is in a range of 0.5 wt% to 1.5 wt%, wherein a content of fluorine in the trench cladding layer is in a range of 1 wt% to 3 wt%, wherein a content of fluorine in the auxiliary outer cladding layer is in a range of 0.5 wt% to 2 wt%, wherein the outer cladding layer is a metal-doped silicon dioxide glass layer, wherein metal dopants doped in the outer cladding layer comprise aluminum and alkali metals, which are one or more of lithium, sodium and potassium, and a total content of the metal dopants is less than or equal to 25 ppm, wherein a content of aluminum is in a range of 1 ppm to 18 ppm, and a total content of the alkali metals is less than or equal to 2 ppm.