Provided is a method of preparing a superabsorbent polymer. In the method of preparing the superabsorbent polymer according to the present disclosure, a polymer resulting from polymerization of ethylene-based unsaturated monomers is subjected to a reassembling process by mixing with a compound of a particular Chemical Formula and water. According to the preparation method of the present disclosure, provided is a method of preparing a superabsorbent polymer having improved water holding capacity and a reduced content of residual monomers, thereby improving quality of final polymer products.