Abstract: Exfoliated graphite is a new kind of composite interfering materials used in electro-optical countermeasure. Exfoliated graphite with different expanding volume was prepared by two-step intercalation, in which the mixture of nitric acid and phosphoric acid and that of nitric acid and acetic acid were employed as intercalating agent step by step, and potassium permanganate was used as oxidant. The microstructure of exfoliated graphite with different expanding volume was analyzed by scanning electron microscope. The infrared screening performance of exfoliated graphite with different expanding volumes was measured by a static method. The results show that the porosity of exfoliated graphite rises with the increasing of expanding volume, the interlayers of graphite are fully opened. And the infrared screening performance enhances with the increasing of expanding volume. When the expanding volume increases from 233 mlg-1 to 450 mlg-1, the infrared screening rate rises from 66.43% to 90.77%.