In this work, a nanocomposite phase change material (PCM) has been designed by combining twodimensionallamellar anhydrous calcium sulfate with polyethylene glycol (PEG). We report a facile strategyto controllably fabricate two-dimensional lamellar anhydrous calcium sulfate (LAH) with the averagethickness of 28.63 nm from phosphogypsum (PG) through ethylenediamine tetraacetic acid disodium(Na2EDTA) induction in glycerol and ethylene glycol solutions at 98 C. The obtained 2D lamellarCaSO4 was a slit-type mesoporous material stacked by the nanosheet of calcium sulfate. It has a specificsurface area of 70.02 m2/g, which is 10 times larger than phosphogypsum. Na2EDTA acts as a crystalhabit-directing agent to regulate crystal morphology through nonclassical nanoparticle-mediated crystallizationprocesses, resulting in the crystalline morphology tending to be lamellar. Lamellar anhydrouscalcium sulfate phase change composites (LAHPCMs) were prepared with 2D lamellar anhydrous nano-CaSO4 and polyethylene glycol (PEG). The LAHPCMs had a high latent heat storage capacity (92.99 J/g). Lamellar anhydrous calcium sulfate phase change composites have good thermal stability and durability,structure stability, and good liquid leakage resistance. These results provide the possibility for phosphogypsumto be used for energy storage and thermal insulation.