Abstract: The direct acting substances of Cuscuta chinensis in vivo were preliminarily identified through the correlation analysis of "metabolites-effect identification" model. The ovariectomized female rats were i.g administered with 95% ethanol extract part, 40% ethanol elution part and n-butanol extract part of Cuscuta chinensis. The serum fingerprints of different parts and times of administration were established by UPLC/Q-TOF-MS. At the same time, serum estradiol (E₂), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were detected. Bivariate correlation analysis and grey correlation analysis were used to screen estrogenic components. The results showed that nine direct acting substances in vivo highly related to estrogen effect were found in the drug containing serum, which were hyperoside, astragalin, methyl quercetin glucuronide, quercetin-diglucuronide, quercetin, apigenin, isoquercitrin, kaempferol glucuronide and kaempferol. We can preliminarily screen out the direct acting substance of estrogen effect of Cuscuta chinensis in vivo based on the research idea of serum spectrum effect correlation. It provides a reliable basis for revealing the estrogeneffective substances of Cuscuta chinensis and confirming the quality markers. This experiment was approved by Harbin University of Commerce Ethics Committees (Approval No. HSDU2020-065).