Objective To explore thyroid glands changes of hyperthyroidism patients before and after 131I treatment by using Color Doppler Ultrasound to measure superior thyroid artery peak systolic velocity (PSV), and the changes of serum thyroid hormone levels to determine the 131I treatment effect in Graves’s diseases. Methods 35 patients with Graves’s diseases were examined by color Doppler Ultrasonography before administration of 131I and 3 months after the treatment. The changes of serum thyroid hormone levels were also measured. Results The serum thyroid hormone levels returned to normal at three month after 131I treatment. There was statistically difference in PSV and serum thyroid hormones before and three months after 131I treatment (P<0.01，P<0.05). Conclusion Color Doppler Ultrasonography is an effective method in PSV measurement. It could be used for the evaluation of 131I therapeutic efficacy of Graver's disease.