〔Abstract〕 Objective To establish a rat model of preeclampsia(PE) in early pregnancy and to observe the changes in phenotype, pregnancy outcome and cognitive ability of offspring. Methods The pregnant rats were randomly divided into model group and control group. Ultra-low dose lipopolysaccharide(LPS)(0.5 μg/kg) and an equal volume of normal saline were injected into the tail vein of pregnant rats on the fifth day of pregnancy. The levels of blood pressure, 12-hour urinary protein, peripheral blood coagulation factors and placental cytokines in the two groups were measured. Furthermore,placental pathology,pregnancy outcomes,and cognitive abilities of offspring were observed. Results Blood pressure and urinary protein levels of model group were significantly higher than those of control group levels. Compared with the control group,the levels of platelet and antithrombin Ⅲ(AT Ⅲ)in the peripheral blood of pregnant rats in the model group were lower than those in the control group,while D-dimer was higher than that in the control group,the weight of the fetus and placenta in the model group decreased(P<0.001),the expression levels of interleukin(IL)-6,tumor necrosis factor α(TNF-α) and interferon gamma(INF-γ) in peripheral blood increased,while the expression level of transforming growth factor β1(TGF-β1) decreased(P<0.001). The water maze test showed that the latency of the offspring of the model group to the platform was longer than that of the control group(P<0.05),while the frequency of crossing the platform quadrant and the time of staying in the platform quadrant of the model group were lower than those of the control group(P<0.05). HE and PAS staining showed that there were infiltration of inflammatory cells in the basal layer of placenta,obvious decrease of blood vessels in labyrinthine area,slight edema of renal interstitium and degeneration of local renal tubular epithelial cells in the model group,while there were no above pathological changes in placenta and kidney in the control group. Conclusion A single injection of LPS in early pregnancy can successfully induce PErelated symptoms and adverse pregnancy outcomes such as fetal growth restriction and lead to the decline of cognitive ability of offspring.