Objective To investigate the application value of multi-slice spiral CT(MSCT) in clinical diagnosis and differential diagnosis of thyroid cancer. Methods 55 patients with suspected thyroid cancer who were admitted into the Central Hospital of Xi'an City Affiliated to Medical College of Xi'an Jiaotong University were selected as the study object. All the patients underwent MSCT examination. The results of surgical or pathological examination were taken as the basis to evaluate the sensitivity, specificity and accuracy of MSCT in diagnosis of thyroid cancer. The coincidence rate in the differential diagnosis of thyroid cancer was recorded. Results The results of pathological or surgical examination showed that in 55 patients with suspected thyroid cancer, there were 32 cases (58.2%) with thyroid cancer and 23 cases (41.8%) with benign lesions; The qualitative diagnostic results of MSCT scan showed that 28 cases were true positive, 20 cases true negative, 3 cases false positive and 4 cases false negative; The accuracy, specificity and sensitivity of CT in the qualitative diagnosis of thyroid cancer were 87.3% (48/55), 87.0% (20/23) and 87.5% (28/32), respectively; The accurate rates in differential diagnosis of thyroid cancer such as papillary carcinoma, follicular carcinoma, medullary carcinoma and undifferentiated carcinoma were 94.7% (18/19), 71.4% (5/7), 66.7% (2/3) and 100.0% (3/3). Conclusion In clinic, MSCT can be used as an effective supplementary method in differential diagnosis of thyroid cancer to improve the pertinence of diagnosis and treatment, so as to improve the time of diagnosis and treatment and improve the prognosis of patients.