To investigate the flavonoids in Rhododendron mariae.The constituents in R. mariae were determined by UPLC/Q-TOF-MS. The chromatographic separation was performed on a C18 column (2.1 mm x 50 mm, 1.7 microm) with a gradient elufion of methanol-water containing 0.1% formic acid. The mass specfrometer eqaipped with elecfrospay ionizafion source was usedas defecfor and operated in data was collected under the positive and negative ion modes.Seven constituents were identified as myricetin-3-O-beta-D-gluconside (1), myricetin-3'-O-beta-D-xylopyraoside (2), hyperoside (3), isoquercitrin (4), avicularin (5), quercitroside (6) and quercetin (7).In this study, the main flavonoids in R. mariae were separated by UPLC, and identified through the information of positive ion and negative ion and relative molecular mass which were determined by Q-TOF-MS. It is an accurate and effective method which can be applied for the constituent identification of R. mariae.