Objective:To investigate the effect of acute hypervolemic hemodilution on deep vein thrombosis(DVT) of elderly patients performed operation on huckle. Methods: Forty ASA Ⅰ or Ⅱ patients aged 65-85 yr weighing 52-83 kg undergoing operation on huckle were randomly allocated into 2 groups (n = 20 each): control group (group C); group AHH(group H). Fluid infusion was performed with 6% HES at 15~20 ml/(kg·h) or normal saline at 0.7~0.8 ml/(kg·h) for 1 h through right internal jugular vein before epidural anesthesia. Venous blood samples were obtained before AHH(T0), the end of operation(T2)and the first day of post-operation(T3)for measurement of hematocrit (HCT), prothrombin time(PT), activated partial thromboplastin time(APTT), fibrinogen(FIB), D dimer, whole blood viscocity at low or high shear rates, plasma viscosity, RBC aggregation and RBC deformation. Another venous blood sample was obtained after AHH (T1) for measurement of hematocrit(HCT). CVP at T0 and T1 were monitored. Two group of patients were survey the deep veins of lower limb by color Doppler ultrasound at the day preoperative and the seventh day post-operation. Results: CVP were stable in all patients. Low or high shear rates,plasma viscosity and RBC aggregation index was significantly decreased in group H at T1 and T3 than at T0. But RBC deformation index was significantly advanced at T2 and T3 than at T0 in group H. Plasma viscosity was significantly decreased at T2 and T3 than at T0 and DD was advanced at T3 than at T0 and T2 in group C. Low or high shear rates and RBC aggregation index was significantly decreased, but RBC deformation index was significantly advanced at T2 and T3 in group H than in group C. DD was decreased at T3 in group H than in group C. The incidence rate of DVT in group H was lower than in group C in the seventh day afteroperation. Conclusion: AHH with HES preoperative improves intraoperative hypercoagulability and sluggish blood flow and decreases the incidence rate of DVT.