Tanacetum vulgare L. (syn.: Chrysanthemum vulgare (L). Bernh) is a perennial medicinal plant with a Euro-Asian type of habitat. Tansy extracts have a wide biological and pharmacological activity. At the All-Russian Institute of Medicinal and Aromatic Plants, on the basis of the butanol fraction of the T. vulgare flowers extract was developed a drug with high choleretic and anti-inflammatory activity. In this regard, the aim of this work was to study the qualitative composition and quantitative content of phenolic compounds of the butanol fraction, which are supposed to determine its biological activity. For this was obtained a phenolic compounds fraction, isolated from the extract of inflorescences of T. vulgare plants grown on the VILAR experimental plot. High-performance liquid chromatography with diode-array detection in combination with high-resolution mass spectrometry (UPLC-PDA-HRMS) was used for the analysis. Our studies have shown that the butanol fraction of T. vulgare contains 7 phenolic compounds, among which myricetin-3-glucoside was detected for the first time. The content of phenolic compounds reaches 90%, while the main compounds are neochlorogenic, 3,5- and 4,5-dicofeylquinic acids, the proportion of which is 69%. Thus, the obtained data indicate that the pharmacological activity of the drug based on the butanol fraction of the extract from tansy flowers is due to the high content of caffeoylquinic acids.