A cold spinning-annealing technique was used to refine grains of U-6.5Nb alloy. The effects of reduction ratio, annealing temperature and holding time on the recrystallized microstructures were studied. The results show that grains become coarse when the annealing temperature was increased from 700 oC to 800 oC, and then to 900 oC, while the reduction ratio has no obvious effects on the recrystallized microstructure. The grain growth indexes at 700 oC, 800 oC and 900 oC are 0.47, 0.31 and 0.34, respectively, and the activation energy for grain growth is 100.4 kJ/mol, indicating that the grain growth of U-6.5Nb alloy is a Nb diffusion-controlled process