Objective To research the influence of clinical efficacy, maternal serum markers and maternal and child outcomes of low molecular heparin calcium in the treatment of early onset severe preeclampsia. Methods 87 early onset severe preeclampsia patients with 26-34 gestational weeks in our hospital between February 2013 and October 2016 were selected. The clinical data of all patients were analyzed by retrospective analysis. According to different treatment methods, they were divided into control group (43 cases) and research group (44 cases). The cases in the control group were treated by traditional method, while the cases in the research group were treated by traditional method combined with low molecular heparin calcium. The clinical efficacy, maternal serum markers and maternal and child outcomes of two groups were compared. Results The 24h urine protein quantity and mean arterial pressure of the two groups before treatment had no statistical difference (P＞0.05). The 24h urine protein quantity and mean arterial pressure of research group after treatment were both much less than control group (P＜0.05). The 24h urine protein quantity and mean arterial pressure of two groups after treatment had statistical difference respectively (P＜0.05). The retinopathy such as I, II and III degree of two groups before treatment had no statistical difference(P＞0.05). The I, II and III degree of research group after treatment had statistical difference with control group(P＜0.05). The amniotic fluid volume and S/D ratio of two groups before treatment had no statistical difference(P＞0.05). The amniotic fluid volume and S/D ratio of research group after treatment were much better than control group (P＜0.05). The coagulation function indexes such as DD, Fg, PLT, APTT and PT and Hcy of the two groups before treatment had no statistical difference (P＞005). The DD, Fg and Hcy of research group after treatment were much lower than control group(P＜0.05). The PLT, APTT and PT of control group after treatment had no statistical difference with pre-treatment(P＞0.05). The serum lipid indexes of two groups before treatment had no statistical difference(P＞0.05). The apo-A and HDL-C of research group after treatment were much higher than control group(P＜0.05). The apo-B, LDL-C, TC and TG of research group were much lower than control group (P＜0.05).The extended gestational age, weight of placenta, weight of neonatus and blood loss after delivery of two groups had statistical difference (P＜0.05). The rate of oligohydramnios (4.55%) in the study group was significantly lower than that of the control group (30.23%) (P＜0.05). The 1 minute Apgar score after birth of two groups had statistical difference(P＜0.05), and the 5 minute Apgar score after birth of two groups had statistical difference(P＜0.05).Conclusion In the treatment of early onset severe pre-eclampsia, low molecular weight heparin Ca can improve the clinical efficacy, improve maternal serum indexes and maternal and child outcomes , and is worthy of clinical promotion.