The present invention relates to a super absorbent polymer and a preparation method thereof. The super absorbent polymer includes surface crosslinked polymer particles prepared by surface crosslinking of particles of a base resin, wherein the base resin is polymerized from a monomer composition including water-soluble ethylene-based unsaturated monomers, and a water-soluble component, wherein the water-soluble component has a ratio (dwt/d(log M)) of 0.9 or less over molecular weights (M) ranging from 100,000 to 300,000 when measured from an eluted solution after swelling the super absorbent polymer for 1 hour, and wherein the content of the water-soluble component is 5% by weight or less, based on the total weight of the super absorbent polymer, when measured after swelling the super absorbent polymer for 1 hour. The super absorbent polymer has excellent liquid permeability even when swollen without a reduction in centrifuge retention capacity or absorbency under load while having improved permeability.