1-[4-(2-Methoxyethyl) phenoxy]-3-[[2-(2-methoxyphenoxy) ethyl]amino]-2-propanol hydrochloride(TJ0711 HC1), a new α1/β 1 receptor-blocking agent, has been found to be effective in the treatment of hypertension in preclinical tests.Two low-level impurities of the order of 0.05% were detected by high performance liquid chromatography (HPLC) method.These two impurities were marked as Imp-1 and Imp-2.The unknown impurities were identified by liquid chromatography-tandem mass spectrometry using electrospray ionization source and Q-trap mass analyzer (LC-ESI-QT/MS/MS).Based on LC-MS/MS data and the background knowledge of the synthetic scheme of TJ0711 HC1, the structures of Imp-1 and Imp-2 were proposed to be 1-[4-(2-Hydroxyethyl)-phenoxy]-3-[2-(2-methoxy-phenoxy)-ethylamino]-2-propanol and 4-{2-Hydroxy-3-[2-(2-methoxy-phenoxy)-ethylamino]-propoxy }-benzaldehyde respectively.Structure confirmation of these two impurities was unambiguously carried out by independent synthesis followed by characterization using mass spectrometry (MS), high resolution mass spectrometry(HRMS) and nuclear magnetic resonance(NMR).