Superabsorbent polymer and preparation method thereof

A method of preparing a superabsorbent polymer, the method comprising:

• A) performing crosslinking polymerization of water-soluble ethylene-based unsaturated monomers having acidic groups which are at least partially neutralized, in the presence of an internal crosslinking agent, to form a water-containing gel polymer including a crosslinked polymer;
• B) drying, pulverizing, and size-sorting the water-containing gel polymer to form a base polymer powder;
• C) performing surface-crosslinking of the base polymer powder by heat treatment in the presence of a surface crosslinking agent to form superabsorbent polymer particles;
• D) adding an aggregation inhibitor and water to the superabsorbent polymer particles;
• and
• E) evaporating the water,
• wherein an aging process is performed at a temperature of 50° C. to 120° C. and a pressure of 100 mm H2O to less than 1500 mm H2O for 5 minutes to 2 hours, after adding water and the aggregation inhibitor.