BackgroundGranulosa cell proliferation and differentiation are essential for follicle development. Breast cancer amplified sequence 2 (BCAS2) is necessary for spermatogenesis, oocyte development, and maintaining the genome integrity of early embryos in mice. However, the function of BCAS2 in granulosa cells is still unknown.ResultsWe show that conditional disruption ofBcas2in granulosa cells caused follicle development failure; the ratio of the positive cells of the cell proliferation markers PCNA and Ki67 were unchanged in granulosa cells. Specific deletion ofBcas2caused a decrease in the BrdU-positive cell ratio, cell cycle arrest, DNA damage, and an increase in apoptosis in granulosa cells, and RPA1 was abnormally stained in granulosa cells. RNA-seq results revealed that knockout ofBcas2results in unusual expression of cellular senescence genes. BCAS2 participated in the PRP19 complex to mediate alternative splicing (AS) ofE2f3andFlt3lmRNA to inhibit the cell cycle. Knockout ofBcas2resulted in a significant decrease in the ratio of BrdU-positive cells in the human granulosa-like tumour (KGN) cell line.ConclusionsOur results suggest that BCAS2 may influence the proliferation and survival of granulosa cells through regulating pre-mRNA splicing ofE2f3andFlt3lby forming the splicing complex with CDC5L and PRP19.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13048-023-01187-1.