Abstract: The calculations of fission gas swelling and hydrostatic pressure in the nuclear fuel were coupled with each other. With the important irradiation creep also considered, the user subroutine was programmed to define its complex mechanical constitutive relation. With the user subroutines of defining all the materials introduced into ABAQUS, the computational method was developed for simulating the meso-scale irradiation induced thermo-mechanical coupling behavior in a UMo/Al dispersion fuel plate, and the hydrostatic pressure effect of the fission gas swelling was analyzed. Comparing the calculated results without considering the hydrostatic pressure effect, the results with the hydrostatic pressure effect show that the irradiation swelling strain in the fuel particles reduces remarkably, the highest temperature decreases, the mechanical interaction between the fuel particles and the matrix is weakened, and the equivalent creep strains in the fuel particles decrease together with the decrease of the maximum Mises stress and the first principal stress in the matrix.