The volatile oil from the medicinal part of Adhatoda vasica Nees was separately prepared by steam distillation methods. The chemical components were analyzed by GC-MS and mass spectral library (NIST08.L, Wiley 275.L) with the area normali-zation method to determine the relative percentage content of each component. 202 peaks were found in the total ion chromatography graph with 51 compounds identified which accounted for 47.83% of the total essential oil. This result showed that there were abundant types of chemical constituents in the volatile oil from the medicinal part of Adhatoda vasica Nees. Investigation of the chemical constituents of Adhatoda vasica Nees may provide some references for the study of its biological activity material base.