Abstract: The characterization of interaction layer（IL） between U-10wt%Mo alloy and LT24 Al was studied in detail in this paper. Sandwich structured U-Mo/LT24 Al diffusion couples were hot pressed at different temperature and pressure for different time. Then they were analyzed by Optical Microscope （OM） and Scanning Electron Microscope （SEM） to observe the width of the IL. The distribution of the diffusion elements and the phases in the IL were determined by Energy Dispersive Spectroscopy （EDS） and X Ray Diffraction （XRD）. Analysis results are as follows: the diffusion manner was reaction diffusion, and diffusion direction mainly was that Al atoms diffused to U-Mo alloy; diffusion mechanism was vacancy diffusion and growth kinetics showed reaction was controlled by the diffusion speed; the IL containing single phase was constituted mainly by （U, Mo） Al₃; the IL containing two phases or more was constituted mainly by （U, Mo） Al₃ and （U, Mo） Al₄ and Al₂₀Mo₂U; and Si impurity in the LT24 Al was easy to enrich in the IL which showed Si added to Al could play positive role on improve compatibility between U-Mo and Al.