Objective, This study aimed to evaluate the effects of acupuncture on embryo implantation and maternal-fetal immune tolerance in rats with ovarian hyperstimulation, identily the mechanisms of acupuncturetreatment, and promote application of acupuncture in the field of assisted reproduction.Methods: Eighty female Wistar rats were randomized into normal (N), model (M), acupuncture treatment (A), and progesterone treatment (P) groups, with 20 rats in each group. An ovarian hyperstimula-tion model was established in groups M, A, and p by the peritoneal injection of pregnant mare serumgonadotropin (PMsG) combined with human chorionic gonadotropin (HCG), Bllateral *Sanyinjiao (SP6)"'Zusanli (ST36)" and *Taichong (LR3)" as acupoints were needled in rats in group A. Rats in group Preceived an intramuscular injection of progesterone (4 mg/kg), All pregnant rats were treated for sevendays, On the 8th day, the pregnant rats were sacrificed for testing. The expression levels of estrogen (Ez)and progesterone (P,) in serum and their receptors in the endometrium, Th1 and Th2 cytokines in serumand endometrium, RT-BM1 (the counterpart of HLA-G in rats) mRNA, Ly49 activating receptors (Ly49s3Ly49s5) and inhibitory receptors (ly49i3, ly49i4, ly49i5) on immunocytes in the matermal-fetal interfacewere detected using ElISA, Western blot, and real-time polymerase chain reaction (PCR).Results: Compared with group N, the pregnancy rate and the number of implanted embryos were signif.icantly decreased in group M (P < 0.05); E, and P, levels in serum, and the protein levels of ER-ar andprogesterone receptor (PGR) in the implantation site of endometrial tissue were significantly reducedin group M (P< 0,05); the contents of INF-y and il-2 in serum and endometrium were signifcantlyincreased, while the contents of iL-4, 1.-6, and il-10 in serum and endometrium were significantly de-creased in group M(P < 0.05). The mRNA levels of RT-BM1, Ly49i3, and Ly49i4 receptors in group M weresignificantly higher than those in group N, whereas the mRNA levels of Ly49i5 and ly49s5 receptors ingroup M were significantly lower than those in group N at the materal-fetal interface (P < 0.05). Thepregnancy rate and number of implanted embryos were significantly higher in group A than in group M(P< 0.05). Serum E, and P, levels were signifcantly higher in groups A and P than in group M (P <0.05). The expressions of ER-a and PcR in the implantation site of endometrial tissue in group A weresignificantly higher than those in group M (P < 0.05). The serum levels of INF-y and iL-2 in group Aand group P were significantly lower than those in group M(P< 0.05), The serum levels of iL-4,IL-6, iL-10 in group A and group P were signiicantly higher than those in group M (P < 0.05). The en-dometrium levels of iNF-y and iL-2 in group A were signifcantly lower than those in group M (P<0.05). The endometrium levels of lL-4, Il-6, lL-10 in group A were significantly higher than thosein group M (P< 0,05), The endometrium levels of INF-yin group p was significantly lower thanthat in group M(P < 0,05), The endometrium levels of il-6 and iL-10 in group p were significantlyhigher than those in group M (P < 0.05), The mRNA levels of RT-BM1 and these Ly49 receptors (exceptthe ly49s3 receptor) at the maternal-fetal interface of groups A and p were higher than those of groupM(P < 0.05).Concusion: Acupuncture can significantly increase the pregnancy rate and average number of implantedblastocysts in rats with ovarian hyperstimulation. This mechanism is related to the effects of acupuncturein upregulating the expression of RT-BM1, regulating the balance of Th1/Th2 cytokines, and upregulatingthe expression of inhibitory receptors in immunocytes.