Molecular dynamic simulation is performed to investigate the thermal properties of U1-xPuxO2 (x=0.07, 0.15, 0.25, 0.5) using the potential of partially ionic model at temperatures ranging from 300 to 3000 K and pressures in a range of 0-1.5 GPa. The results indicate that the lattice parameters decrease linearly with Pu ratio increasing under different temperatures. The linear expansion coefficient increases with Pu ratio increasing. The isothermal compressibility decreases with Pu ratio decreasing. In addition, the experience functions of lattice parameter and linear expansion coefficient are also derived.