Abstract:ln this paper, 38 samples of Mentha canadensis Linn. from Yunnan Pronvince were studied. The essential oil yields and their chemical constituents were determined. The essential oil yield are about 0. l8% ~ 0.5%, l00 kinds of chemical constituents were identified from the essen-tial oil, which are menthol, menthone, piperitenone epoxied, L-limonene, linaiool and so on. The chemical classification of the planting M.canadensis belong in carvone series. The chemical classi- fication of the wild M.canadensis belong in menthone series, but some of the wild M.canadensis belong in mescellaneous series.