ObjectiveTo systematically evaluate the effect of low molecular weight heparin (LMWH) on the prognosis and bleeding risk  in patients with sepsis. MethodsCochrane Library Databases， PubMed，Embase，VIP Data，Wanfang Data，China National Knowledge Infrastructure（CNKI），and China Biology Medicine disc（CBMdisc）between January 1995 and September 2017 were retrieved, retrieved literatures were about randomized controlled clinical trial of LMWH for treatment of sepsis. According to inclusion and exclusion criteria, literatures were screened, extracted, and conducted quality evaluation, RevMan 5.3 software was used to perform Meta analysis. Results1 016 patients in 19 studies were included in Meta analysis. 28day mortality was compared among 19 studies and found that LMWH could reduce 28day mortality in patients with sepsis (RR=0.52，95％CI［0.43-0.63］，P<0.001)；subgroup analysis included 2 studies, which showed that LMWH could reduce 28day mortality in patients with sepsis combining acute lung injury(RR=0.40，95％CI［0.21-0.75］，P=0.004)；4 studies compared the length of stay in intensive care unit (ICU) and found that LMWH had no obvious effect on length of stay in ICU (MD=-0.84，95％CI［1.95-0.26］，P=0.14)；15 studies compared effect of LMWH on APACHE Ⅱ score and found that LMWH could reduce the APACHE Ⅱ score of patients with sepsis after 7 days(MD=-0.64，95％CI［0.93-0.34］，P=0.00)；4 studies compared the effect of LMWH on the incidence of disseminated intravascular coagulation (DIC) and found that LMWH could reduce the incidence of DIC in patients with sepsis (RR=0.34，95％CI［0.18-0.67］，P=0.002)；12 studies compared the effect of LMWH on bleeding and found that LMWH could increase the risk of bleeding in patients with sepsis (RR=2.74，95％CI［1.60-4.71］，P=0.00). ConclusionLMWH can reduce 28day mortality and improve the prognosis of patients with sepsis, but can increase the incidence of bleeding.