Abstract:The plant of Ledum palustre L. var. angustum N. Busch is distributed in northeast China, it is used as a folk medicine. The essential oil was extracted by steam distilation from its leave. Twenty seven components have been idendified by GC-MS and other methods, such as: myrtenal, cuminal, ρ-cymene, β-thujene etc. Their contents in the oil have been determined also.