To study the fundamental physical properties and intermolecular interaction of energetic materials under the loading temperature， the first-principle calculation was performed combined with zero-point energy and temperature effect corrections. The accuracy of lattice parameters at experiment temperature （173 K） can be significantly improved， and the deviations between the calculated lattice parameters and available experimental data are within 1%. The unit cell volume change with temperature is relatively reasonable compared with the experimental value at 0-500 K， and their deviation is mainly from the lack of interactions between phonons. Furthermore， the basic thermodynamic properties such as heat capacity， entropy and bulk modulus were predicted， and the results indicate that the lattice parameters and thermal expansion coefficient of FOX-7 have strong anisotropy in 0-500 K. Especially， the thermal expansion coefficient of interlayer direction is higher than that of inner layer direction， which is closely related to the molecular configuration and stacking. Importantly， when the temperature reaches 200 K， the shrinkage of thermal expansion coefficient of FOX-7 is related to the rotation of NO₂ group. The NO₂ group would regulate the intermolecular interaction by changing the dihedral angle with the molecular plane， thereby triggering potential phase transformation of FOX-7. In addition， the bulk modulus under the adiabatic conditions is consistent with the experimental values reasonably， and the evolution of adiabatic bulk modulus with temperature reflects the softening behavior of FOX-7 at the finite temperature. With the increase of temperature， the calculated heat capacity and entropy increase gradually， showing obvious numerical differences under the constant volume and pressure due to the anharmonic effect.