The present invention relates to a super absorbent polymer and a preparation method thereof. The super absorbent polymer according to the present invention is characterized in that it includes a crosslinked polymer prepared by surface crosslinking of a base resin polymerized from water-soluble ethylene-based unsaturated monomers, and a water-soluble component, in which the water-soluble component has a ratio (dwt/d(log M)) of 0.9 or less over weight average molecular weights (M) ranging from 100,000 to 300,000 when measured after swelling the super absorbent polymer for 1 hour. According to the present invention, provided is a super absorbent polymer having excellent liquid permeability even when swollen without a reduction in centrifuge retention capacity or absorbency under load while having improved permeability.
