Objective To investigate the effect of low molecular weight heparin (LMWH) on the prevention of deep venous thrombosis in patients with lower limb fracture.Methods 213 cases of peripherally inserted central venous catheter after deep venous thrombosis of lower extremity fractures from February 2014 to October 2016 in our hospital orthopedic surgery were retrospectively analyzed,according to whether patients with low molecular weight heparin were divided into two groups,which did not use low molecular weight heparin in patients with 104 cases as control group,using the low molecular weight heparin in 109 patients as study group,with seven days of treatment as the observation period, the blood rheology indexes of the two groups of patients and the incidence of deep vein thrombosis were analyzed.Results After treatment, the blood viscosity, fibrinogen, and plasma D-dimer levels of the whole blood decreased in both groups, and the levels of plasma D-dimer were significantly lower in the study group than in the control group (P<0.05);the plasma viscosity of the study group was significantly lower than that of the control group (P <0.05).After treatment,the recurrence rate of deep venous thrombosis in the study group was significantly lower than that in the control group ( P<0.05 ); The effective rate of treatment group was 96.33%was significantly higher than the control group 76.92%(P<0.05);study group incidence of adverse reactions 1.83%was significantly lower than the control group 7.69%( P <0.05 ) .Conclusion Low molecular weight heparin can effectively improve the indexes of Hemorheology in patients with lower limb fracture after central venous catheter puncture, reduce the risk of deep vein thrombosis, and have a clear preventive effect.