Background: To explore whether maternal obesity inhibits placental angiogenesis through downregulation of Sirtuin 1/Peroxisome proliferator-activated receptor-γ coactivator-1α (SIRT1/PGC-1α) signaling pathway.Methods: In a rat model of pre-pregnancy obesity, rats were sacrificed at embryonic day (E)18.5. Maternal characteristics were measured. Placentas were collected to observe the pathological changes and angiogenesis using hematoxylin-eosin (HE) staining and platelet endothelial cell adhesion molecule-1 [PECAM-1/CD31 (CD31)] immunohistochemical (IHC) staining, and the expression of the SIRT1/PGC-1α signaling pathway was also analyzed using western blotting and quantitative real-time polymerase chain reaction (qPCR). In in vitro experiments, human umbilical vein endothelial cells (HUVECs) were incubated under high fat conditions. We activated and inhibited the SIRT1/PGC-1α signaling pathway to determine the proliferation, angiogenic tube formation, and migration capacity of endothelial cells. Cell counting kit-8 (CCK-8) assays, tubule formation assays, and scratch wound-healing migration assays were also performed. Results:In vivo results showed that compared with the control group, the high-fat diet (HFD) group were heavier and their plasma triglyceride and total cholesterol contents were higher. The ratio of fetal weight to placental weight was reduced in the HFD group compared to the control group. In the HFD group, placental angiogenesis was decreased, and the SIRT1/PGC-1α signaling pathway was down-regulated compared with that in the control group. The results of in vitro experiments showed that SRT1720 reduced SIRT1/PGC-1α and vascular endothelial growth factor (VEGFA) expression inhibition induced by high fat stress, while EX-527 increased SIRT1/PGC-1α and VEGFA expression inhibition. Compared with the control group, maternal obesity impaired placental angiogenesis and reduced the proliferation and migration of HUVECs. Conclusions:The results suggest that maternal obesity impairs placental angiogenesis. They also provide experimental evidence that activation of the SIRT1/PGC-1α signaling pathway improves angiogenesis in vitro.