The coalescence behavior of nanoscale xenon (Xe) bubbles in U-Mo alloy matrix is investigated by the classical molecular dynamics (MD) simulations with the general utility lattice program (GULP).The embedded atom method (EAM) potential proposed by Smirnova et al.is used to describe the U-Mo-Xe system.The spherical cavity is created by the method of removing a same proportional number of U and Mo atoms.The evolution process of Xe bubbles coalescence in U-Mo alloy fuel matrix are shown that the critical temperature of the bubbles coalescence increase with increasing the initial distance between the centers of two bubbles.When the initial distance between the centers of two bubbles are 3.0, 2.6, and 2.2 nm, the critical coalescence temperatures are 1000, 600, and 400 K, respectively.The evolution processes of small Xe bubble in the U-10Mo alloys fuel matrix are similar although the Xe bubbles and the Xe atoms under the different initial conditions.The surface energy of U-Mo alloys is estimated between 0.45 and 0.50 J/m2 approximately, which is in accordance with the theory value of 0.43 and 0.5 J/m2 used in literature.