Objective To analyze clinical risk factors for radioiodine(RAI)-refractoriness of DTC with distant metastasis and do survival analysis.Method The clinical data of 77 differentiated thyroid cancer(DTC) patients with distant metastasis admitted to the department of radionuclide therapeutics of Qilu Hospital from Jan 2002 to Sep 2015 were collected to make the retrospective analysis by dividing into radioiodine-refractory(RAI-R) group and radioiodine-efficient(RAI-E) group.Result (1)In DTC patients treated by 131I, there are 77(7.15%) patients with distant metastasis.Among DTC with distant metastasis, 25(32.47%) patients are identified as RAI-R DTC with average age of (56.2±16.0) years old, median age of 57 years old, and male-to female ratio of 1∶2.57.(2)Univariate analysis shows that age of distant metastasis older than 45 years and pathological type of follicular thyroid cancer(FTC) are two risk factors related to RAI-refractoriness.Logistic regression analysis indicates that age of distant metastasis older than 45 years and pathological type of FTC are the independent risk factors for RAI-refractoriness of DTC with distant metastasis.(3)3-year and 5-year survival rates of the 25 RAI-R DTC patients with distant metastasis are 75% and 62%,while RAI-E DTC patients were all alive.The survival of RAI-R DTC with distant metastasis is significantly worse than RAI-E DTC with distant metastasis.Conclusions (1)In the DTC with distant metastasis, the rate of RAI-R DTC is not low, and it is 32.47%.Females of RAI-R DTC are more than males.(2)Age of distant metastasis older than 45 years and pathological type of FTC are independent risk factors for RAI-refractoriness of DTC with distant metastasis.(3)The survival rate of RAI-R DTC with distant metastasis was significantly lower than that of RAI-E DTC with distant metastasis.