Preeclampsia is a pregnancy-specific disease, which has become an essential cause of perinatal and neonatal death. Gut microflora becomes the regulator of host immunity through the metabolic pathway. Epidemiological studies provide convincing evidence that vitamin D supplementation can prevent the onset of preeclampsia. However, research on the microbial mechanisms and effective treatment strategies for placental inflammation induced by lipopolysaccharide is lacking. In this study, pregnant rats were induced by LPS to establish a rat model of preeclampsia. 16-sequence analysis was used to determine the composition of microflora in feces. In addition, the protective effect of vitamin D supplementation on LPS-preeclampsia rats was evaluated. The results showed that the blood pressure and creatinine of pregnant rats in the LPS group were significantly higher than those in the control group. Additionally, LPS disturbed the intestinal microbial community and reduced microbial diversity. Vitamin D supplementation improves the symptoms of preeclampsia, increases the abundance of intestinal beneficial flora, normalizes the level of inflammatory factors LPS-induced by inhibiting the TLR4/MYD88/NF-KB pathway, and effectively resists the disturbance of uterine spiral artery remodeling induced by LPS. This study established that vitamin D-mediated microbial mechanisms and their inhibition are potential therapeutic targets for the treatment of preeclampsia.