Abstract: In this paper,the interaction behavior of U-Mo/Al was studied with the diffusion-couple method,and the couple was continuously jointed by hot-pressing with special device.Annealing experiments were accomplished in a vacuum hot-pressing furnace,and at 550～570℃ for 5～21hours.The results show that the morphology and composition of interaction Layer depend on the interaction layer thickness.The con-tent of U（Mo） and Al is mutational at the interface of U-Mo/interaction layer/Al.The layer close to U-Mo side is mainly composed of product（U,Mo）Al 3,while the Al side is composed of（U,Mo）Al 4 and UMo 2 Al 20.Diffusion process of U-Mo/Al is Al immigrating over the Al/U-Mo original interface into U-Mo side and re-acting with U-Mo,subsequently the interaction layer is growing into Al.