This paper compared chemical constituents and antimicrobial activity of the volatile oil from Solidago canadensis and S.decurrens.The volatile oils were respectively obtained from fresh leaves of the two species with hydrodistillation.S.canadensis a newly extended invasive species in east China and S.decurren is a traditional Chinese medical plant in wild.Major chemical constituents of the volatile oil were identified and analyzed by GC-MS analyses.Antimicrobial activity was tested by the disc diffusion method.The results exhibited that the greatest component of the volatile oil from leaves of S.canadensis was(-)-germacrene D(44.24%).The greatest component of the volatile oil from leaves of S.decurrens was δ-elemene(21.73%).High content of a component acted as anticancer activity in the oil from S.decurrens was detected.The antibacterial activity of the volatile oil from S.canadensis was lower than that from S.decurrens.Chemical constituents of the volatile oil from S.canadensis were obviously different from that of the volatile oil from S.decurrens.The volatile oil from S.canadensis could not replace the volatile oil from S.decurrens on values of medicines.