c-axig highly oriented crystallite films of AIN have been prepared on Si substrates by d. c. planar magnetron sputtering. The analysis for the infrared absorption spectrum indicated the frequencies of crygtal lattice longitudinal and transverse vibration modes being ag 2.5×1013Hz and 1.8×1013Hz. The optical phonons at 297, 512, 607, 656, 832cm-1 have been observed in Eaman spectrum of AIN thin filmg. The modes of these phonong were determined by comparision with those of the given binary compounds crysbalized wurtzite structure. Further analysis shows that A1N is a crystal with which interaction forces were mostly electrostatic in original and the highest frequency of the phonona was direobly proportional to r-3/2M-1/2.