Taurine, acting as a free amino acid, is widely distributed and plays multiple functions, including its regulating effect on estrogen synthesis in ovary. However, the mechanisms of taurine regulating estrogen synthesis in granulosa cells are not well understood. In this study, we identify whether microRNA-7a2 (miR-7a2) is involved in the signaling of taurine regulating estrogen synthesis in mouse granulosa cells for the first time. The results demonstrated that taurine transporter (TauT) co-localized with miR-7a in mouse ovarian granulose cells. Further, taurine treatment markedly enhanced the expression of miR-7a and Cyp19a1 in mouse ovaries and increased serum 17β-estradiol (E