This paper aims at detecting chemical components of the volatile oil in nine samples of Lemiaceae plants by GC/MS with the help of heuristic evolving latent projection (HELP) resolutions. The analyzing process of HELP was described in detail. Relative contents of oil constituents were computed from the total volume integration. More than 70 relatively common components were identified and the main compounds are terpenes and their derivatives. Eucalyptol (relative content 0.10%～1.01%) and Linalool (0.11%～3.05%) are the common main compounds of the nine plants. Compared to simply using GC-MS, the results of the essential oil obtained by the analysis of GC-MS combined with chemometric resolution method are more reliable and accurate.

Key words: Lemiaceae, volatile oil, GC/MS, heuristic evolving latent projection