Abstract: Objective: to investigate the characteristics of parathyroid adenoma on multi-slice spiral CT (MSCT) and 3 dimension (3D) reformatted images, evaluate this technique in diagnosing parathyroid adenoma preoperatively. Materials and Methods: CT findings were retrospectively analyzed in 63 patients with pathologically conformed parathyroid adenoma (PTA). Results: 62 (98.4%) cases of PTA were solitary, 1 (1.6%) case with multiple nodules, there were 64 lesions altogether, 45 (70.3%) of which located in the trachea-esophageal sulcus at the thyroid lower pole, 15 (23.4%) of which located in the trachea-esophageal sulcus at the thyroid upper pole, 4 (6.3%) lesions were ectopic adenoma. On plain CT scan, all lesions showed homogeneous or heterogeneous soft tissue density, 33 (51.6%) lesions of which displayed the "short-line sign". In the early phase of contrast enhanced CT, significant enhancement was found in all lesions, in the later phase, the density difference between the tumor and surrounding tissues became lesser. However, there was less change in the "short-line sign" after administration of contrast enhancement. Conclusion: MSCT and 3D reformation can demonstrate the location, size, shape and texture of PTA, as well as the relationship between the tumor and adjacent structures. There would be important for the qualitative diagnosis and localization in patient with PTA. 3D reformatted images showed long axis of 53 (82.8%) lesions parallel to the long axis of the body, 3D reformation can display the relationship between lesions and the surrounding tissue.