Preparation method of super absorbent polymer

A method for preparing superabsorbent polymer comprising:

• conducting crosslinking polymerization of water soluble ethylenically unsaturated monomers having acid groups of which at least a part are neutralized, in the presence of a polymerization initiator and an internal crosslinking agent, to form hydrogel polymer comprising a crosslinked polymer of water soluble ethylenically unsaturated monomers;
• drying, grinding and classifying the hydrogel polymer to obtain base resin powder;
• conducting first surface crosslinking of the base resin powder while raising to a first temperature, in the presence of a first surface crosslinking agent to form a first surface crosslinked base resin powder;
• and
• conducting second surface crosslinking of the first surface crosslinked base resin powder at a second temperature, in the presence of a second surface crosslinking agent, to form superabsorbent polymer particles,
• wherein the first temperature is 180° C. or more, and the second temperature is 120° C. to 150° C., and
• the second surface crosslinking agent comprises an epoxy-based compound having larger weight average molecular weight than that of the first surface crosslinking agent, and capable of forming a covalent bond at the second temperature.