A method of preparing a superabsorbent polymer, including the steps of: preparing a hydrous gel phase polymer by thermal polymerizing or photo-polymerizing a monomer composition including a water-soluble ethylene-based unsaturated monomer and a polymerization initiator; drying the hydrous gel phase polymer; milling the dried polymer; classifying the milled hydrous gel phase polymer into two or more grades by particle size; adding a surface cross-linking agent to each hydrous gel phase polymer classified into two or more grades; the step of feeding the hydrous gel phase polymer classified into two or more grades to a surface cross-linking reactor, after the step of adding the surface cross-linking agent; and carrying out a surface cross-linking reaction of the hydrous gel phase polymer to which the surface cross-linking agent is added, wherein the content of the fine powder having the particle size less than 150 μ m included in the final superabsorbent polymer is 0.1 to 1.2 weight%, wherein the classifying step is carried out into two grades of the particles having a particle size of less than 150 μ m and the particles having a particle size of 150 μ m to 850 μ m, or into three grades of particles having a particle size of less than 150 μ m, particles having a particle size of 150 μ m or more and less than 300 μ m, and particles having a particle size of 300 μ m to 850 μ m, or into four grades of particles having a particle size of less than 150 μ m, particles having a particle size of 150 μ m or more and less than 300 μ m, particles having a particle size of 300 μ m or more and less than 600 μ m, and the particles having a particle size of 600 μ m to 850 μ m. preparing a hydrous gel phase polymer by thermal polymerizing or photo-polymerizing a monomer composition including a water-soluble ethylene-based unsaturated monomer and a polymerization initiator; drying the hydrous gel phase polymer; milling the dried polymer; classifying the milled hydrous gel phase polymer into two or more grades by particle size; adding a surface cross-linking agent to each hydrous gel phase polymer classified into two or more grades; the step of feeding the hydrous gel phase polymer classified into two or more grades to a surface cross-linking reactor, after the step of adding the surface cross-linking agent; and carrying out a surface cross-linking reaction of the hydrous gel phase polymer to which the surface cross-linking agent is added, wherein the content of the fine powder having the particle size less than 150 μ m included in the final superabsorbent polymer is 0.1 to 1.2 weight%, wherein the classifying step is carried out into two grades of the particles having a particle size of less than 150 μ m and the particles having a particle size of 150 μ m to 850 μ m, or into three grades of particles having a particle size of less than 150 μ m, particles having a particle size of 150 μ m or more and less than 300 μ m, and particles having a particle size of 300 μ m to 850 μ m, or into four grades of particles having a particle size of less than 150 μ m, particles having a particle size of 150 μ m or more and less than 300 μ m, particles having a particle size of 300 μ m or more and less than 600 μ m, and the particles having a particle size of 600 μ m to 850 μ m.