Objective To evaluate the effect of aspirin and low molecular weight heparin combined with pregnancy outcomes and uterine artery blood flow indexes in high-risk pregnant women with early-onset preeclampsia (EOP). Methods: This study enrolled 102 high-risk EOP pregnant women admitted between October 2023 and December 2024. Using a randomized block design, the participants were evenly divided into a control group (n=51) and an experimental group (n=51). The control group received aspirin monotherapy, while the experimental group received aspirin plus low molecular weight heparin. Key outcomes included: ① Clinical efficacy; ② Uterine artery blood flow parameters before and after treatment [pulse index (PI), resistance index (RI), S/D ratio]; ③ Coagulation function indicators [prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FIB), D-dimer (D-D)]; ④ Pregnancy outcomes; ⑤ Maternal and neonatal complications. Results: The total effective rate of treatment in the study group was significantly higher than that in the control group (P<0.05). After treatment, the PI, RI and S/D of both groups decreased significantly compared with those before treatment, and the PI, RI and S/D of the study group after treatment were significantly lower than those of the control group (P<0.05). After treatment, the PT and APTT in both groups were significantly prolonged compared with those before treatment, and the FIB and D-D were significantly increased compared with those before treatment. Moreover, the changes in the levels of PT, APTT, FIB and D-D in the study group after treatment were significantly greater than those in the control group (P<0.05). The gestational weeks at termination of pregnancy in the study group were significantly longer than those in the control group, and the birth weight of newborns was significantly higher than that in the control group (P<0.05). The rates of preterm birth, fetal growth restriction, placental abruption and postpartum hemorrhage in the study group were significantly lower than those in the control group (P<0.05). However, there was no significant difference in the rates of neonatal asphyxia and fetal distress between the two groups (P>0.05). Conclusion: The combination of aspirin and low molecular weight heparin can improve the efficacy, optimize uterine artery blood flow and coagulation function, significantly reduce the risk of maternal and infant complications such as preterm birth, and improve pregnancy outcome in high-risk EOP pregnant women.