Abstract: A new inclusion compound of 2C₂H₆N₄S₂^-·2(C₂H₅)₄N⁺·H₂O was prepared and characterized by X-ray single crystal crystallography. Additionally, the configurations of dithiobiurea and its related anion were discussed with the oretical calculation. Crystal data:monoclinic system, a space group of P2₁/n, a=1.2002(61) nm, b=1.6676(61) nm, c=1.6031(11) nm, β=103.5770(10)°, Z=4, V=3.1192(5) nm³, R₁=0.0650. By observing the structure, it was found that dithiobiurea anions interacted with each other to generate the host layer structure with the existence of N-H…S hydrogen bonds and the only water molecule further consolidated the anionic layer by O-H…N interactions. Consecutively, the tetraethylammonium cations, as the couterions, were accommodated between the host layers to yield the final typical sandwich-like inclusion compound. Noticeably, the neutral molecule of dithiobiurea and its related anion showed totally different spatial configurations in both the crystal structures and the calculating results.