The invention discloses a molecular marker for diagnosis and treatment of pituitary adenoma. Pituitary adenoma is a common intracranial benign tumor and can induce endocrine symptoms as well as intracranial hypertension and change of vision and view. Experiments prove that the expression of PAEP gene in the pituitary adenoma tissue is up-regulated, and the expression of the PAEP gene can inhibit the proliferation of pituitary adenoma cells and promote the apoptosis of the pituitary adenoma cells. The invention provides a new molecular means for the diagnosis and treatment of pituitary adenoma.