Abstract: To investigate the properties of β-HMX, molecular simulation was implemented to calculate the isotherms of β-HMX at different temperatures using COMPASS force field. The simulation results were fitted to Birch-Murnaghan equation of state and Hugoniot relations. The results indicate that the effect of temperature on the isothermal equations of state consists in the following ways: β-HMX gets more compressible at higher temperatures, the thermal expansion of β-HMX weakens at high pressure and pressure-induced changes of the lattice parameters of β-HMX possess the property of anisotropic compression without change with the temperature.