Abstract： Objective： To observe the clinical efficacy of Buqi Huoxue Prescription in the prevention of deep venous thrombosis （DVT） of the lower extremities in critically ill patients. Methods：Clinical data of 70 critically ill patients of qi deficiency and blood stasis type treated at People's Hospital of Jingning She Autonomous County from July 2018 to June 2023 were collected. The patients were divided into the control group and the observation group according to treatment methods， with 35 cases in each group. The control group received conventional anticoagulation therapy， while the observation group received Buqi Huoxue Prescription in addition to the control group's treatment. After two weeks of treatment，the two groups were compared in terms of DVT incidence，traditional Chinese medicine syndrome score， hematocrit， blood viscosity， homocysteine （Hcy）， fibrinogen （Fib）， prothrombin time （PT）， activated partial thromboplastin time （APTT），and incidence of drug-induced adverse reactions. Results：After treatment，the incidence of DVT was 2.86% （1/35） in the observation group and 22.86% （8/35） in the control group， with a statistically significant difference between the two groups （P＜0.05）. After treatment， traditional Chinese medicine syndrome scores in both groups decreased compared with those before treatment，and the traditional Chinese medicine syndrome score in the observation group was lower than that in the control group， with statistically significant differences （P＜0.05）. After treatment， hematocrit， blood viscosity， and Hcy levels in both groups decreased compared with those before treatment （P＜0.05）；and the levels of these indicators in the observation group were lower than those in the control group，with statistically significant differences （P＜0.05）. After treatment，Fib levels in both groups decreased compared with those before treatment （P＜0.05），while PT and APTT increased compared with those before treatment （P＜0.05）；the Fib level in the observation group was lower than that in the control group （P＜0.05）， and PT and APTT levels were prolonged compared with those in the control group （P＜0.05）. During treatment， the incidence of adverse reactions was 4.71%（ 2/35） in the observation group and 11.43%（ 4/35） in the control group，with no statistically significant difference between the two groups （P＞0.05）. Conclusion： On the basis of routine DVT prevention， the addition of Buqi Huoxue Prescription can reduce the incidence of DVT in critically ill patients， alleviate traditional Chinese medicine syndrome manifestations， and improve hemorheology and coagulation function， with good safety.