Abstract: Objective To explore the effect of low molecular weight heparin combined with magnesium sulfate on fetal growth restriction and the effect of perinatal prognosis. Methods Total 200 pregnant women with restricted fetal growth were selected in the obstetrics department of Jinhua People's Hospital in February, 2016 to February, 2018, and divided into the observation group (100 cases) and the control group (100 cases) according to the random digital table method. The control group was treated with low molecular weight heparin on the basis of routine treatment, while the observation group was treated with magnesium sulfate on the basis of the control group. The average weekly uterine height and fetal growth, amniotic fluid index and biophysical score, neonatal outcome (neonatal asphyxia rate, perinatal mortality, neonatal Apgar score, Full moon sample, premature infant incidence) were compared between the 2 groups of parturients. Results The average weekly uterine growth and fetal growth (fetal head circumference, abdominal circumference, biparietal diameter and long increase of femur) were higher in the observation group than in the control group, P<0.05. There was no significant difference between the 2 groups of amniotic fluid index and biophysical score before the treatment, P>0.05; the amniotic fluid index and Biophysics in the observation group were better than the control group after treatment. The score of the neonatal Apgar in the observation group was higher than that of the control group, and the neonatal asphyxia rate and perinatal mortality in the observation group were 1.0% and 0.0%, in the control group were 7% and 4%, respectively, P>0.05. The incidence of Full moon sample in the observation group was 2% lower than that in the control group (9%), P<0.05; the incidence of morning infants in the observation group was 4%, which was lower than that in the control group (12%), P<0.05; The neonatal weight and gestational age of the observation group were better than those in the control group, P<0.05. Conclusion Low molecular weight heparin combined with magnesium sulfate is effective in the treatment of fetal growth restriction. It can effectively promote fetal growth and development, and has high safety. It is worthy of clinical application.