OBJECTIVE To screen the active ingredient with estrogenic effect from total flavonoids of Cuscutae Semen. METHODS The estrogenic effect of total flavonoids from 10 batches of Cuscutae Semen was evaluated with mouse uterus coefficient and endometrial thickness as evaluation indexes， establish its fingerprint and calibrate the common peak. Common peak and spectrum-effect relationship of the above two indicators were analyzed by bivariate relationship analysis and grey correlation analysis to screen active components with estrogenic effect. UPLC-Q-TOF-MS technology was used to characterize the active components. RESULTS The estrogenic effect of total flavonoids from 10 batches of Cuscutae Semen was good. Twenty-eight and thirty-three common peaks of total flavonoids in Cuscutae Semen were obtained in the positive and negative ion modes respectively. The constituents represented by peaks 7，10，12-16，26 in positive ion mode and peaks 2，5，8，9，12，16，19，22-26 in negative ion mode were highly correlated with the estrogenic effect of total flavonoids from Cuscutae Semen. Further identification showed that the active substances with estrogenic effect from the total flavonoids of Cuscutae Semen were 5，7，3′， 4′-tetramethoxyflavone， 6- O-（trans） p-coumarin-furanfructose-（2→1）-glucopyranoside， rutin， kaempferol-3，7-diglucoside， apigenin-7-O-glucoside， hyperoside， baicalin， quercitin， quercetin， apigenin， kaempferol， isorhamnetin， rhododendron， isoquercetin， kaempferol-3-furan arabinoside， 2，6-octadecanediacetylic acid. CONCLUSIONS A total of 16 chemical components with estrogenic effect are screened from total flavonoids of Cuscutae Semen in the study， which can provide reference for the development of phytoestrogens.