Pituitary adenomas secreting adrenocorticotropin (ACTH),also known as Cushing's disease (CD),cause hypercortisolemia due to excessive secretion of ACTH stimulating bilateral adrenal cortical hyperplasia, which is the most common cause of endogenous hypercortisolemia. ACTH-secreting pituitary adenomas can lead to electrolyte disorders, sugar and lipid metabolism disorders and a series of serious clinical symptoms, involving multiple organs and systems in the whole body. Transsphenoidal neuroendoscopic surgery is the first-line treatment for ACTH-secreting pituitary adenomas and can achieve a high remission rate, but postoperative recurrence and persistent status are still an unsolved problem in the treatment of ACTH-secreting pituitary adenomas. The pathological evaluation of ACTH-secreting pituitary adenomas has important value in determining the nature of the lesion, predicting the prognosis and selecting the drug therapy. This article reviews the progress in the pathologic evaluation of ACTH-secreting pituitary adenomas, including new immunohistochemical markers and microscopic features.