Abstract: In order to clarify the effect of volatile oil from Zanthoxylum armatum v.novemfolius induced by conventional pulverization, the volatile oil content was determined by steam distillation, and the chemical composition was detected by gas chromatography-mass spectrometry ( GC-MS) .Compared with the whole grain, the loss of volatile oil reached up to 34.2% in fine powder ( 80 mesh, the national standard) .And the main loss components during pulverization were identified as enol compounds.Though the loss of volatile oil in coarse powder ( 10 mesh) was not obvious, more kinds of chemical composition were detected in it.According to all these results, the finer pulverization, the more volatile oil loss.But chemical components were extracted efficiently under the appropriate pulverization.