Abstract: Objective: To explore the effects of the number and quality of embryos transferred from fresh embryo with antagonist regimen on pregnancy outcome of assisted reproductive technology. Methods: The data of 308 patients with fresh embryo transfer cycle antagonist regimen were retrospectively analyzed.According to the number of embryos transferred and number of high-quality embryos,they were divided into 3 groups:group A(transfer of 1 high-quality embryo),group B1(transfer of 1 high-quality embryo +1 non-high-quality embryo),and group B2(transfer of 2 high-quality embryos).The differences of general information,ovulation induction,laboratory data and pregnancy outcome were compared among all groups. Results: The infertility years in group A was lower than that in group B2(P<0.05).The number of transferable embryos,high-quality embryos and frozen embryos in group A were higher than that in group B1,the number of transferable embryos and high-quality embryos in group A were lower than that in group B2,and the number of eggs obtained,number of oocyte with metaphase Ⅱ(MⅡ),number of embryos with two pronuclear(2PN),transferable embryos,high-quality embryos and frozen embryos in group B1 were lower than those in group B2(P<0.05 to P<0.01).The differences of positive rate of human chorionic gonadotropin(β-hCG),clinical pregnancy rate,implantation rate and live birth rate were statistically significant among three groups(P<0.01),and the above indexes in group B2 were higher than those in groups A and B1(P<0.05).The ovarian hyperstimulation syndrome(OHSS) and multiple pregnancies occurred in group B2.The results of logistic regression analysis showed that the number of antral follicle number(AFC),number of high-quality embryos and transfer of two high-quality embryos were the protective factors of clinical pregnancy(P<0.05-P<0.01). Conclusions: For patients using GnRH antagonist protocol during fresh embryo transfer cycle,transfer one high-quality embryo and one non-high-quality embryo can not improve the clinical pregnancy rate.Although adding one high-quality embryo to transfer can improve the clinical pregnancy rate,the multiple pregnancy rate will also increase significantly.The incidence of OHSS in GnRH antagonist protocol is lower.