Objective：The phenotype of female mice was studied by constructing Id3-Gdf9-Cre+ conditional knockout（CKO）mice to further determine the effect of differentiation inhibitor Id3 on female mice fertility. Methods：The development of follicles was detected in the ovaries of the conditional knockout mice with Id3-Gdf9-Cre+ by HE staining and follicle counting. The oocyte maturation was detected by maturation experiments in vitro and superovulation experiments in vitro. And mice fertility was detected by mating experiment. Results：The results of qPCR and Western blot showed that we had successfully knocked out Id3 in oocytes. HE staining was performed on 3 weeks and 8 weeks mice ovaries and the follicles were counted at various levels，and the follicles developed at all levels were normal. Oocyte maturation experiments and superovulation experiments showed that oocyte maturation was normal in vitro. Mating experiment showed that CKO mice have normal fertility. Conclusion：Under normal feeding conditions，conditional knockout of Id3 does not affect normal follicles development or fertility of female mice.