Abstract: 【Objective】This study aimed to investigate the effects of Notch1 on the proliferation and differentiation of bovine follicular granulosa cells （GCs）， reveal its biological role in bovine ovarian function and reproductive regulation， and provide a theoretical basis for elucidating the molecular mechanisms of bovine follicular development.【Method】Six healthy cows were selected to collect ovarian tissues for primary passage separation and culture of GCs. Immunohistochemical staining was used to detect the localization of Notch1 protein in ovarian tissues； EdU staining was used to detect proliferation activity of GCs； flow cytometry was used to detect the proliferation process of GCs； Western blotting was used to detect the relative expressions of proteins related to proliferation and differentiation of GCs.【Result】Immunohistochemical staining revealed high expression of Notch1 protein in bovine follicular GCs. EdU staining showed that Notch1 activation promoted proliferation of GCs， while the use of DAPT to inhibit Notch signaling pathway could inhibit GC proliferation. Flow cytometry analysis showed that Notch1 activation promoted the transition of GCs from G1 phase to S phase. Western blotting results showed that： Notch1 activation significantly increased the relative expressions of Notch1，CCND1， CCNE1， CDK2， CDK4， CDK6， CYP19A1， and StAR proteins （P<0.05， the same below） and extremely significantly increased the relative expressions of CCND2， CCND3， and LHCGR proteins （P<0.01， the same below）； inhibition of the Notch signaling pathway significantly decreased the relative expressions of CCND1， CCND2， CCND3， CCNE1， CDK2， CDK4， LHCGR， CYP19A1， and StAR proteins， and extremely significantly decreased the relative expressions of Notch1 and CDK6 proteins； Notch1 activation promoted the proliferation and differentiation of GCs.【Conclusion】Notch1 is highly expressed in bovine follicular GCs. Notch1 activation promoted the transition of GCs from G1 phase to S phase， and up-regulates the relative expression of cell proliferation-related proteins CCND1， CCND2， CCND3， CCNE1， CDK2， CDK4， CDK6， and differentiation-related proteins LHCGR， CYP19A1， and StAR. Notch1 is an important factor regulating the proliferation and differentiation of bovine follicular GCs， and the Notch signaling pathway mediated by it plays a key regulatory role in ovarian development and reproductive function.