Abstract: A model for the swelling behavior of fission gas in the range of low temperature of irradiated uranium dioxide fuel is established.In this paper,the finite difference method is adopted to compile a computational program and quantitatively calculated the fractions of fission gas as solid solution in UO₂,the density and average radius of intragranular bubbles and their contributions to the swelling of uranium dioxide fuel.in different burn-ups and temperatures of uranium dioxide fuel.The calculation shows that this model can be used to predict the fission gas swelling of uranium dioxide fuel versus burn-up in the range of low temperature.