Objective To evaluate the value of enhanced CT scan in differential diagnosis of thyroid neoplasm.Methods 27 cases of thyroid neoplasm including 18 cases of thyroid adenoma and 9 cases of thyroid papillary carcinoma proved by operation and pathology were retrospectively analyzed.Results In 18 cases of thyroid adenoma,there were 12 cases with well defined enhanced ring and 6 cases with enhanced nodule in adenoma.In 9 cases of thyroid papillary carcinoma,there were no complete enhanced ring on the wall,and 4 cases with enhanced nodule on the wall,there were 7 cases with fine granular or plague like calcifications and 4 cases with sign of surrounding structures involved.Conclusion In CT diagnosis of thyroid neoplasm,enhanced scan is necessary for characterization of the tumors.Invasion of surrounding structures is a characteristic sign of malignancy.Nodules enhancement of the tumor wall accompanied with granular calcification is the signs of thyroid papillary carcinoma,tumor sharp wall is the sign of adenoma.