To evaluate clinical characteristics, recurrence risk factors, and radioiodine treatment response in post-total thyroidectomy papillary thyroid micro-carcinoma patients. Subject and method: 214 post-total thyroidectomies papillary thyroid microcarcinoma underwent radioiodine therapy at least once at the Nuclear Medicine Department - 108 Military Central Hospital were analyzed for some clinical characteristics, recurrence risk factors, and radioiodine therapy response. Then, compare these characteristics in patients with tumor sizes ≤ 5mm and 5-10mm. Result: In 214 patients in our study, 81.8% were female, 79.4% were < 55 years old, primary tumor lesions were mainly unifocal and unilateral, 68.7% had capsular invasion, but only 24.3% had a capsular extension, 10 (4.7%) had distant metastases mostly detected on radioiodine whole-body scans. The capsular invasion and the dose I-131 usage were relevant to the lymph node metastasis and the radioiodine therapy response, respectively. The subgroup analysis showed that some clinical and histopathological characteristics were not significantly different; however, the recurrence risk and radioiodine therapy response classification were significantly different between the two groups. Conclusion: Despite the subcentimeter size of the primary tumor, it is clear that a considerable proportion of these patients have encapsulation, lymph nodes, or even distant metastasis. The capsular invasion and the dose I-131 usage were relevant to the lymph node metastasis and the radioiodine therapy response, respectively. The recurrence risk and radioiodine therapy response were significantly different between ones with primary tumor size ≤ 5mm and 5-10mm.