Objective：To compare the effectiveness of different dosages of Oxytocin on uterine fibroids vessels. Methods：Totally 120 patients with uterine leiomyomas were randomly divided into three groups. Oxytocin at concentrations of 0.12，0.24 U/min and 0.36 U/min were infused respectively into patients in the three groups. Fibroid feeding arteries changes before and after the intravenous in－fusion of Oxytocin were observed by using color doppler ultrasound. The differences of arterial changes responding to the use of Oxytocin in all three groups were analyzed. Indicators of blood pressure，pulse，respiration and adverse events were recorded dur－ing the procedure and within 3 months of follow-up. Results：Peak systolic velocity，mean blood flow velocity，diameter and blood flow of the fibroid feeding arteries of patients in all three group were decreased，but resistance index was increased with statistical differ－ences compared with that before the infusion（P＜0.05）. But there was no significant statistical difference of arterial changes before and after the intravenous infusion of Oxytocin among the three groups（P ＞0.05）. No adverse event was observed in all patients. Conclu－sions：Oxytocin can reduce blood supply of the fibroids. 0.12 U/min Oxytocin intravenous infusion could be the most favorable dosage for ultrasound ablation in the treatment of uterine fibroids.