To explore preventive efficacy of Salviae Miltiorrhizae and Ligustrazine Hydrochloride Injection combined with low molecular weight heparin calcium on blood flow of deep venous thrombosis of lower extremity after spinal fracture.Methods:From January 2016 to September 2017，105 patients with spinal fracture admited in the orthopedics department of the hospital were selected.They were randomly divided into 2 groups according to different strategies of preventing deep venous thrombosis of lower extremity.The treatment group(n=54)was treated with the Salviae Miltiorrhizae and Ligustrazine Hydrochloride Injection combined with the low molecular weight heparin calcium.The control group(n=51)was treated with the low molecular weight heparin calcium alone.Index changes of hemodynamics，hemorheology，coagulation function and the occurrence of deep venous thrombosis of lower extremity were observed before the treatment and 10 days after the treatment.Results: 1)After the treatment，the hemodynamic parameters in the treatment group-Ratio(085±025)，SVC(892±132)mmHg，MVO(762±117)mmHg，VRT(1483±356)s were significantly higher than those in the control group(P<005). 2)After the treatment，in the treatment group，the hemorheological indexes-erythrocyte sedimentation rate(1047±284)mm/h，high shear rate(392±059)mPa·s，low shear rate(883±073)mPa·s，hematocrit(4671±520)%，whole blood viscosity(362±057)mPa·s，erythrocyte aggregation index(281±066)were significantly lower than those in the control group(P<005). 3)After the treatment，the coagulation function in the treatment group-APPT(3271±425)s，PT(1747±284)s were significantly higher than those in the control group; FIB(262±037)g/L，D-D(291±032)mg/L were significantly lower than those in the control group(P<005). 4)In the treatment group，the positive rate(556%)of deep venous thrombosis was significantly lower than that in the control group(1569%)(P<005).Conclusion:For the prevention of deep venous thrombosis in lower extremity after spinal fracture，the adjuvant therapy of Salviae Miltiorrhiza and Ligustrazine Hydrochloride Injection can be used on the basis of low molecular weight heparin calcium.It can effectively promote the recovery of hemorheology and hemodynamics in the patients.It has obvious efficacy on improving coagulation function and preventing deep venous thrombosis of lower extremity.