The invention relates to an antiferroelectric high-energy-density ceramic material and a preparation method thereof. The general formula of the composition is (1-x)PbHfO[3-x]PbMg0.5W0.5O3, wherein x represents the mol percent of PbMg0.5W0.5O3, and x=0.01-0.25. By adopting a two-step solid-phase sintering process to prepare the ceramic material, the composition is controlled, so that the critical electric field of the antiferroelectric ceramic is obviously lowered, and the withstand voltage strength is enhanced, thereby implementing high-energy-density application in the room temperature environment. The high-energy-density ceramic capacitor dielectric material has the advantages of low sintering temperature, high withstand voltage strength (up to 130 kV/cm) and high energy density (up to 1.39 J/cm<3>), can be used for preparing high-energy-density multilayer ceramic capacitors, and has favorable application prospects. The antiferroelectric high-energy-density ceramic material has the characteristics of simple technique and stable performance, and is suitable for industrial popularization.