A mini-spherical model of fuel was designed and the irradiation swelling of U10Mo-Al dispersion fuel was simulated by the model. The results show that a higher irradiation temperature leads to a more obvious swelling of fuel. With the fission rate increasing, below the turning point of burnup the rate of swelling is nearly the same; however, beyond the turning point of burnup, the rate of swelling is slower at higher fission rate. The predicted results are well consistent with the experimental in a reasonable range.