N-substituted 3,3-dinitroazetidine, represented by the following Chemical Formula I, as an energetic plasticizer, and a method for preparing the same through a coupling reaction in which the energetic material 3,3-dinitroazetidine or an acid salt thereof serves as a nucleophile for the α,β-unsaturated carbonyl compound as a substrate are provided. wherein R1 and R2 are each independently alkyl, substituted alkyl, aryl, substituted aryl, arylalkyl, substituted arylalkyl, heteroaryl, substituted heteroaryl, heteroarylalkyl, substituted heteroarylalkyl, hydroxy, nitro, or a halogen atom, wherein the substituent of the substituted radicals is selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, alkoxy, thioalkyl, amino, nitro, hydroxy, a halogen atom, and a combination thereof.