Objective: To investigate the predictive factors for incidental thyroid carcinoma through its ultrasonic and pathological features. Methods: The clinicopathologic data of 541 patients with thyroid cancer treated in the First Affiliated Hospital of Harbin Medical University between January 2014 and October 2014 were retrospectively analyzed. Of the patients, 108 cases were incidental thyroid carcinoma (observational group), and 421 cases were non- incidental thyroid carcinoma (control group). Differences in clinicopathologic features between the two groups of patients were compared. Results: There was significant difference between the two groups in the proportions of age, number of lesions, pathological classification, structure of lesions, whether or not combined with benign thyroid disease, presence or absence of calcification, color of lesion, aspect ratio of nodules, elasticity score, boundary conditions, echo intensity, whether or not lymph node dissection of the central compartment was performed (all P<0.05). Logistic regression analysis revealed that follicular carcinoma, absence of calcification, aspect ratio less than 1, clear boundaries, non-hypoecho, elasticity score less than 3 and the ratio between the diameter of tumor and tumor-bearing nodule less than 30% were predictive factors for incidental thyroid carcinoma (all P<0.05). Conclusion: Follicular carcinoma, absence of calcification, length to width ratio less than 1, clear boundaries, non-hypoecho, elasticity score less than 3 and the ratio between the diameter of tumor and tumor-bearing nodule less than 30% are predictive factors for incidental thyroid carcinoma.