Objective To study the effect of low molecular dextran on venous thromboembolism of patients after radical correction of cavitas pelvis. Method This propective randomized case-control study consisted of two hundred and seventy six postoperative patients with high risk of venous thromboembolism,low molecular dextran was used as prophylactics for venous thromboembolism, and the change of blood routine, coagulation function and morbidity of deep vein thrombosis were analyzed. Result After operation, D-dimer、Coagulation Factor Ⅱ and blood viscosity in patients using low molecular dextran was lower than those in control group (P<0.05). Conclusion Coagulation funtion can be improved by using low molecular dextran after radical correction of cavitas pelvis,postoperative venous thromboembolism can be decreased.