Abstract: The neutron inelastic scattering spectrum of dibenzo--18--crown--6 was measuredwith the Be filter detector spectrometer at room temperature. The rang of theenergy spectrum is from 3.6 to 168 mev. The result was compared with theinfrared data. By neutron method. we observed two intense peaks at 142 cm ~(-1)and 37 cm~(-1), which come from the vibration of the crystal lattice or molecularrotation. The observed peak positions are difficult to reach by general infraredtechnique.