Embryo implantation and decidualization are crucial for successful pregnancy, which include multiple genes and signaling pathways, while the precise mechanism regarding embryo implantation and decidualization has yet to be explored. The GABA which activates GABA_A or GABA_B receptors has been found playing an important role in early pregnancy. Here we seek to investigate whether GABA_B receptors participate in embryo implantation in mice. This study first characterized the spatiotemporal expression pattern of GABA_B receptors in the uterus during the peri-implantation period and found that GABA_B1 expression was drastically upregulated in stromal cells on days 4-6, a period of embryo implantation and early stages of decidualization. Embryo delayed implantation and oil-induced decidualization models were further used to con firm that the GABA_B1 was associated with embryo implantation and decidualization. We also found estrogen or progesterone had no directly effect on expression of GABA_B1 in ovariectomized model. Because we were unable to detect significant GABA_B2 which couples with GABA_B1 to form whole GABA_B receptors, and the agonist and antagonist of whole GABA_B receptors had weak effect on the proliferation and differentiation of stromal cells as well, we excluded the possibility whole GABA_B receptors function, and concluded it should be non-classical signals of GABA_B1 involving in embryo implantation and decidualization. Future studies should focus on investigating the roles and mechanisms of GABA_B1 during embryo implantation and decidualization.