Objective To screen out the active parts of the water extract of Flos Mume against a cell model of Alzheimers disease (AD) caused by β-amyloid (Aβ), and to identify the chemical constituents of the parts with relatively good activity. Methods The active parts of Flos Mume were extracted with water and different concentrations of ethanol, and then AB-8 macroporous adsorption resin was used to enrich and prepare the samples of the four elution parts of Flos Mume. The SH-SY5Y cell model of AD induced by Aβ was established to investigate the activity of the samples from different parts of Flos Mume, and ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry was used to identify the constituents of the parts with relatively good activity. Results The eluates obtained by the different concentrations of ethanol had a relatively good inhibitory effect on SH-SY5Y cytotoxicity induced by Aβ (P<0.05) in a concentration-dependent manner, and the eluates obtained by 60% and 90% ethanol had a significant effect (P<0.05). A total of 24 compounds were identified for the two active parts, including 16 flavonoids, 4 phenylpropanoids, and 4 other compounds. A total of 14 constituents were identified from the two active components, mainly flavonoids. Conclusion The 60% ethanol elution part and the 90% ethanol elution part of Flos Mume are the active parts for its anti-Aβ protein toxicity effect, and flavonoids are the main material basis of these active parts.