Abstract: The compatibility of U-Mo alloy and Zirconium alloy was studied in this paper. The diffusion-couple was prepared by coated hot rolling and annealed at 750℃ and 850℃ for 10 and 50 hours. The result shows that the diffusion-layer has delaminated between U-Mo alloy and Zirconium alloy, and the diffusion-layer has a complicated composition with the Mo₂Zr second precipitate. XRD result shows that the composition of diffusion-layer is the Mo₂Zr, UZr₂ and U. The diffused mechanism of U-Mo and Zirconium is that the atom of U and Mo diffuse into Zirconium alloy, then Mo and Zr form Mo₂Zr firstly and the U continuously through out Mo₂Zr to form γ-（U,Zr） solid-solution. The U-Mo alloy has good compatibility with Zirconium alloy.