Objective: To analyze and compare the chemical components of oleum rhododendri daurici from different regions of Heilongjiang province. Method: The volatile oils were extracted by steam distillation. Chromatographic peak of complete separation were analyzed by capillary gas chromatography-mass spectrometry (GC-MS) and overlapping chromatographic peaks analyzed by heuristic evolving latent projections (HELP) of chemometrics. The relative content of each component in volatile oil was calculated by normalization of peak area

and the method of principal component analysis is taken to analyze the data of qualitative and quantitative. Result: A total of 85 components were identified

of which 32 compounds were existed in all the samples. According to chemical components

15 samples were divided into four categories. No germacrone was detected in 6 samples. Conclusion: More information can be obtained from oleum rhododendri daurici

combined GC-MS analysis with chemometric method.