The change in crystal structure of α-2,4-dinitroanisole (α-DNAN) under the different conditions of temperatures and pressures was studied by the method of combining theory and experiment, and its application potential in the low velocity layer of plane wave lens was discussed. The results of comprehensive experiments (variable temperature X-ray diffraction, high pressure Raman spectra) and theoretical calculations (density functional theory, molecular dynamics) show that the α-DNAN crystals can exist stably in the range of the studied temperatures（298-358 K） and pressures（0.0001-1.5 GPa）, and the phase transition phenomenon does not occur. Under temperature-pressure coupling, the a-axis direction of the α-DNAN crystal is most easily expanded or compressed due to the large amount of π-π action. The b-axis direction is most difficult to be compressed due to its strong steric hindrance. At lower pressures (0.0001, 0.6 GPa), the density of α-DNAN crystals decreases with temperature increasing. Under the condition of 0.2 GPa, the density of α-DNAN crystals at 313 K is lower than that of at 308 K and 323 K, and the mechanical properties are also correspondingly worse, which indicates that the change of crystal structure is the result of the synergistic effect of pressure and temperature.