To investigate the mechanism of Rhaponticum uniflorum(L.)DC.regulating casein synthesis in mammary glands of mammary animal, in this study, the effects of ethanol extract from Rhaponticum uniflorum(L.)DC.(25,50,100,200,400,600,800 μg/mL)on the viability and proliferation ability of mammary epithelial cells in dairy goat were detected by using a cell activity analyzer.The concentration of ethanol extract not inhibiting cell growth and proliferation was selected to study the effect of ethanol extract on the mRNA expression of casein synthesis related genes of mammary epithelial cells in dairy goat.The mRNA expression levels of CSN1S1,CSN1S2,CSN2,CSN3,STAT5,JAK2,mTOR,4EBP1,S6K1 in mammary epithelial cells were detected by qRT-PCR. The results displayed that higher doses(200—800 μg/mL) of ethanol extract from Rhaponticum uniflorum(L.)DC. significantly inhibited the viability and proliferation ability of mammary epithelial cells in dairy goat (P<0.05).Thus,the epithelial cells were treated with 25,50,100 μg/ mL ethanol extract in subsequent experiments.The ethanol extract obviously up regulated the mRNA expression of CSN1S1,CSN1S2,CSN2,CSN3 genes and the genes related to casein synthesis such as STAT5,JAK2,mTOR,S6K1 (P<0.05). But the ethanol extract significantly down regulated the mRNA expression of 4EBP1 gene (P<0.05).This study shows that the ethanol extract from Rhaponticum uniflorum(L.) DC.can promote the synthesis of casein by regulating the expression of genes related to casein synthesis in mammary epithelial cells of dairy goats.