Objective: To explore the clinical value of low molecular weight heparin(LMWH) plus low dose aspirin(LDA) in preventing twin pregnancy with preeclampsia high risk factors. Methods: From January 2013 to December 2017, the twin pregnancy cases with preeclampsia high risk factors who were diagnosed in Shanxi Rongjun Hospital were randomly divided into two groups according to the order of the treatment.The observation group(n=53) used LMWH plus LDA to prevent preeclampsia, while the control group(n=53) used LDA alone.The incidence of preeclampsia and pregnancy outcome were compared between the two groups. Results: The incidence of severe preeclampsia in the observation group(5.7%) was lower than that in the control group(18.9%)(χ²=4.296, P<0.05), and there was statistically significant difference in the delivery time between the two groups(χ²=7.993, P<0.05). While the incidence of preeclampsia, placental abruption, postpartum hemorrhage and FGR between the two groups had no statistically significant differences (all P>0.05). The proportion of NICU transferred fetus in the observation group(18.3%) was lower than that in the control group(30.7%)(χ²=4.289, P<0.05). There were no statistically significant differences in perinatal mortality and neonatal asphyxia(all P>0.05). Conclusion Compared with using the LDA alone, LMWH plus LDA prevention can effectively reduce the incidence of severe preeclampsia in twin pregnancies; at the same time, it also can delay the delivery time and reduce the rate of NICU transferred.