Abstract: Graves' disease is the most common etiology of thyrotoxicosis. ¹³¹I therapy is widely used to treat Graves' disease but may fail or course hypothyroidism. Thus, the study of prognostic factors of Graves' disease is of great clinical value. Research suggests that several factors, including the patient’s age, gender, course, serological indices, ¹³¹I therapy dose, thyroid volume and weight, effective half-life of ¹³¹I, technetium-99m pertechnetate thyroid uptake rate, radioactive iodine uptake rate, and thyroidal ¹³¹I turnover rate, may have important impacts on the results of ¹³¹I therapy; indeed, some of them remain controversial. The aim of this paper is to summarize the prognostic factors of ¹³¹I treatment to help clinicians decide on the best treatment route.