OBJECTIVE： To investigate the anticoagulation effects of warfarin on the lower extremity deep venous thrombosis（LEDVT）， and to analyze its influential factors， in order to provide scientific basis for individualized medication of warfarin in the clinic. METHODS： Totally 140 cases of LEDVT were selected and treated with warfarin on the and day after admission with initial dose of 5.0 mg， qd， 2.5 mg for following 2 days，orally， qd. The dose of warfarin was adjusted 72 h after medieation according to INR of patients. The dose of warfarin wasused as the maintenance dose when INR reached the anticoagulant target. Clinical data of patients were recorded， and blood biochemical indexes and coagulation function were detected. The influential factors of anticoagulation effects were analyzed by multiple-linear regression. At the same time， the results of INR were recorded before medication and 24， 48， 72 h after medication. RESULTS： INR of patients receiving warfarin had the potential to increase， compared to before medication； 24， 48， 72 h after medication， INR value showed a gradual upward trend， without statistical significance （P＞0.05）. The change of INR within 24 h after medication was less than that within 24-48 h after medication； the change of INR within 24-48 h after medication was less than that within 48-72 h after medication， with statistical significance （P＜0.01）. The influence of various factors on the anticoagulant effect of warfarin in descending order was as follows： age， weight， low density lipoprotein cholesterol， plasma albumin， disease duration. Among them， age and low density lipoprotein cholesterol were positively correlated with anticoagulation， while body weight， plasma albumin and disease duration were negatively correlated with anticoagulation. CONCLUSIONS： Both age and body weight are the main influential factors for anticoagulation effect of warfarin. Individualized medication should be implemented in order to improve the anticoagulation effects of warfarin.