Abstract： Objective： To observe the clinical effect of the therapy of Biejia Decocted Pills combined with low molecular weight heparin calcium on malignant tumors deep venous thrombosis of lower extremities. Methods： A total of 63 patients with malignant tumors deep venous thrombosis of lower extremities were divided into the trial group (31 cases) and the control group (32 cases) according to the random number table method. The two groups were treated with routine antineoplastic therapy，based on which the control group was given subcutaneous injection with low molecular weight heparin calcium， and the trial group was additionally treated with Biejia Decocted Pills based on the treatment of the control group. Before and after treatment， the traditional Chinese medicine (TCM) syndrome scores， coagulation function indexes，including activated partial thromboplastin time (APTT)，prothrombin time (PT)， international normalized ratio (INR)，D-dimer (D-D) and blood platelet count (BPC)，indexes of hemorheology， including whole blood high shear viscosity，whole blood medium shear viscosity，whole blood low shear viscosity and plasma viscosity， inflammatory factors， including tumor necrosis factor- α (TNF- α) and interleukin- 6 (IL- 6) and the thigh of affected limb were compared between the two groups； the clinical effects and incidence of adverse reactions in the two groups were evaluated. Results：With 1 case in the trial group and 2 cases in the control group being dropped out ， finally 30 cases in the trial group and 30 cases in the control group were included into the study. The total effective rate was 93.33% in the trial group，higher than that of 66.67% in the control group (P＜0.05). After treatment，the APTT，PT and INR in the two groups were higher than those before treatment (P＜0.05)，and the D- D and BPC were lower than those before treatment (P＜0.05)；the APTT，PT and INR in the trial group were higher than those in the control group (P＜0.05)，and the D- D and BPC were lower than those in the control group (P＜0.05). After treatment， the TCM syndrome scores， whole blood high shear viscosity， whole blood medium shear viscosity，whole blood low shear viscosity and plasma viscosity，and the levels of TNF-α and IL-6 in both groups were lower than those before treatment (P＜0.05)，and the TCM syndrome scores，indexes of hemorheology and levels of inflammatory factors in the trial group were lower than those in the control group (P＜0.05). After treatment，the thighs at 15 cm above and 10 cm below the patella of affected limb in the two groups were shortened when compared with that before treatment (P＜0.05)， and the thigh of affected limb in the trial group was shorter than that in the control group (P＜0.05). There was no adverse reaction in the two groups. Conclusion：The therapy of Biejia Decocted Pills combined with low molecular weight heparin calcium has a definite curative effect on malignant tumors deep venous thrombosis of lower extremities， which can effectively improve the coagulation function and indexes of hemorheology， decrease the levels of inflammatory factors and reduce the swelling degree of the affected limb with good safety.