Objective To investigate the MRI diagnostic effect of thyroid nodule. Methods The clinical data and MR imagings of 120 patients with thyroid nodules admitted in our hospital from January 2015 to January 2017 were analyzed retrospectively. Results MRI diagnoed 159 thyroid nodules among 120 patients, including 80 cases of benign nodules and 79 cases of malignant nodules. Pathology detected 161 thyroid nodules, of which 89 were benign nodules and 72 were malignant nodules. The nodule morphology, boundary, cystic degeneration, enhancement schedule, and diffuse thyroid enlargement of benign nodules and malignant nodules were significantly different (P<0.05), no difference was found in the nodules number (P<0.05). Of 29 cases of thyroid cancer, the detection rate was 24.17%. Among them, 15 cases located at left lobe, 13 cases located at right lobe, and 2 cases located at isthmus. The short diameter of nodules ranged from 0.61 to 5.94 cm with an average of (0.48±0.10) cm. There were 19 cases of ipsilateral lymph node metastases, 10 cases of bilateral lymph node metastases, 7 cases of the trachea violations, and 14 cases of local skin and soft tissue violations. There were 13 cases with T1WI high signal and 5 cases with T2WI high signal, 4 cases with low or equal signal on T1WI, and 7 cases with low or equal signal on T2WI. Among the benign nodules, there were 54 right leaves and 26 left leaves. The short diameter of the nodules ranged from 1.20 to 5.41 cm with an average of (3.59±0.18) cm. There were 15 cases with high T1WI or 15 cases with high signal on T2WI, 21 cases with signal on T1WI, and 9 cases with signal on T2WI. Conclusion MRI can effectively distinguish the benign and malignant thyroid nodules. Malignant thyroid nodules mostly manifest as irregular nodule margins, blurred boundaries, nodular cystic changes, inconsistent enhancement of enhanced scans, and tendency to diffuse diffuse thyroid lesions. The benign nodule is characterized with clear edges and equal MRI signals.