【Objective】 To lay a foundation for the subsequent use of multi-omics methods to explore the metabolic pathways and regulatory mechanisms of important medicinal compounds of Tilia miqueliana Maxim., and provide a theoretical basis for the harvesting of flowers, the chemical composition of T. miqueliana flowers and the content changes of its signature components, flavonoids, in different growing stages were investigated. 【Methods】 The 10-year-old T. miqueliana was used as the test material, this experiment conducted to explore chemical components of flower and flavonoid content differences using ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). 【Results】 The results showed that, (1) A total of 46 compounds were identified, including 13 organic acids and their derivatives, 4 coumarins and their derivatives, 1 ester, and 28 flavonoids. (2) The flower opening stage was the cut-off point for significant changes in metabolites. Compared with the bud stage, the metabolites changed more significantly during flowering. (3) Multiple comparison analysis showed that the content of 26 flavonoids differed significantly (P < 0.05) in flowers at different phenological stages. Afzelin, kaempferitrin, quercitrin, hesperidin taxifolin and apigenin 7-O-glucuronide were higher at the flower opening stage. Final bud stage had higher concentrations of proanthocyanidin A2 and three proanthocyanidin trimers. 【Conclusion】 The development status could be an important factor in determining the content of secondary metabolites in the flowers of T. miqueliana. The signature compound at the final bud stage was proanthocyanidin A2, and at full bloom stage is apigenin-7-O-glucuronide, both of them were valuable for harvesting.