Objective To investigate the efifcacy and adverse effect of ultrasound-guided injection of different dosage of thrombin in the treatment of femoral artery pseudoaneurysm formed after vascular intervention. Methods 48 cases of femoral artery pseudoaneurysm after vascular interventional operation in our hospital were randomly divided into two groups according to the dosage thrombin given.Under ultrasound guidance, patients in the observation group (n=24) received injection thrombin 100U/ml while patients in the control group received injection of thrombin 500U/ml.All the operational procedures were identical between the 2 groups. Results No statistical differences were found in clinical characteristics, total number injection needed and operation time between two groups.Recurrence pseudoaneurysm was noted in 1 cases in the observation group. 2 cases of superifcial femoral arteries thrombin and 1 case of fever were recorded in control group. There was no difference in adverse event rates between the 2 group. Conclusions Ultrasound-guided injection with low dose thrombin in the treatment of post interventional femoral artery pseudoaneurysm is equally effective as higher dose.