Binary solid noble gases have great applications and are considered as model systems for understanding the van der Waals interactions. The hitherto unknown binary Xe-He phase diagram was investigated through a first-principles swarm structural search. One energetically stable stoichiometry of XeHe2, adopting a hexagonal AlB2-type structure, is identified. The structure and phase transition sequence of XeHe2 are distinct from those in NeHe2 (MgZn2 -> MgCu2) and ArHe2 (MgCu2 -> AlB2-type). Moreover, pressure-induced electronic properties of XeHe2 are in sharp distinction with NeHe2, while similar to ArHe2. Our work enables a potential opportunity for understanding the structure and property of the binary Xe-He solid. (C) 2015 Elsevier B.V. All rights reserved.