OBJECTIVE: To explore the blood circulation activating effect and mechanism of Sanqi(Radix Notoginseng) in vivo, using a venous thromboembolism(VTE) rat model.METHODS: We established the VTE rat model, and then intervened with low molecular weight hepa-rin(LMWH), as well as low, medium and high doses of Sanqi(Radix Notoginseng), to observe the blood circulation activating effect of Sanqi(Radix Notoginseng) on VTE rats.RESULTS: After the treatment with high concentrations of Sanqi(Radix Notoginseng), the pulmonary thromboembolism was alleviated, and the lower limb thrombosis was markedly improved. Moreover, the expression quantities of plasma activated partial thromboplastin time, prothrombin time and D-dimer, as well as endothelin, von Willebrand factor, and plasminogen activator inhibitor-1 in thrombosis segment tissues were markedly down-regulated; while those of nitric oxide and tissue-type plasminogen activator were up-regulated. After low and medium concentration Sanqi(Radix Notoginseng) treatment, no obvious improvement was observed in each index. Moreover, the high concentration Sanqi(Radix Notoginseng) showed comparable efficacy to the positive drug LMWH.CONCLUSION: This data suggests that high concentration of Sanqi(Radix Notoginseng) is effective in preventing and treating VTE.