Abstract: Following the idea of micromechanics of particle reinforced composites,for the dispersion fuel plate,a representative element is chosen to study the thermal-mechanical coupled behaviors using the gradually increasing fission pressures which are corresponding to fission density and burnup,to simulate the mechanical contribution produced by particle fission to the Al matrix.The effects of the fission pressure,the thermal strain and the non-uniform distribution of the particles along the thickness on the swelling are investigated in details.Besides,the Mises stress distribution in the matrix is analyzed.The research results indicate that（1） the higher the particle volume fraction is,the quicker the velocity of particle swelling,（2） with the increasing of the fission pressures,the velocity of particle swelling increases sharply and the particles do not remain round,（3） on the conditions of normal work and for the chosen parameters,the effects of the thermal strain on the total deformation are not evident,（4） when the fission pressure is not big,the non-uniformity hardly affect particle swelling,however,with the increasing of fission pressure,the swelling of the non-uniformly distributed particles are distinctly higher than the uniformly distributed ones and this phenomenon is more and more evident,and（5） the stress distribution of the matrix is not spherical symmetry.