Abstract:Objective:Analyzing the constituents of the essential oil from Waichangpu(dried rhizome of Anemone altaica,often mistakenly called “Jiujiechangpu”).Method:Separating and identifying the constituents by GC MS.Result:Twenty two compounds from the essential oil from Waichangpu were separated and identified,the main ones being cedrenol(23.69%),β-eudesmol(8.49%),elemol(2.80%),hexadecanoic acid(4.77%) and 9,12-octadecadienoic acid(14.93%).Conclusion:The essential oil content is very low in Waichangpu,and the oil structure of Waichangpu is obviously different from that of Shichangpu(dried rhizome of Acorus tatarinowii, whose another name is Jiujiechangpu).The present study provides a chemical basis to support the view that Waichangpu should not be confused with Shichangpu as a medicinal herb.