Empty saddle syndrome is a condition in which the subarachnoid space extends into the saddle, causing the pituitary gland to shrink and compress and the saddle to enlarge, which can cause certain clinical symptoms, either primary or secondary to pituitary tumor surgery or radiation therapy. The normal saddle-diaphragm foramen only accommodates the passage of the pituitary stalk. If the saddle diaphragmatic foramen is larger, there is a cavity around the pituitary stalk, and because the pituitary envelope has some continuity with the intracranial arachnoid membrane, under the pulsating pressure of cerebrospinal fluid, cerebrospinal fluid can enter the saddle through this arachnoid channel, making the saddle full of cerebrospinal fluid and forming the so-called arachnoid cyst. Most of the arachnoid cysts are located in front of the pituitary gland, pressing the pituitary gland to the posterior and being compressed, and finally pressing against the dorsum of the saddle, making the pterygoid saddle anatomically cavernous and contributing to its enlargement. In the case of increased intracranial pressure, such as hydrocephalus, brain tumor, benign cranial hypertension, obesity, and chronic heart failure, it is more favorable for cerebrospinal fluid to be squeezed into the saddle, which leads to the formation of empty saddle. When the pituitary gland volume is reduced, it is also easy to promote the formation of empty butterfly saddle, such as: 1, after repeated expansion of pituitary gland volume; 2, after spontaneous necrosis degeneration of pituitary tumor; 3, after vascular pituitary atrophy caused by Sihan syndrome; 4, when the pituitary gland primary atrophy such as children pituitary gland function is insufficient; 5, hypothyroidism leads to pituitary hyperplasia after thyroxine treatment and volume reduction. Clinically, it is more common in middle-aged women and may present with headache, visual impairment, and visual field defects. Visual field impairment mainly involves the nasal side or both nasal sides and is irregular and variable. Some patients may have endocrine symptoms such as amenorrhea lactation or simple lactation, hypopituitarism, etc. Primary empty saddle generally does not require treatment, such as the complication of cerebrospinal fluid nasal leakage should be treated by butterfly surgery, with obvious anterior pituitary hypopituitary function, can be hormone replacement therapy. Secondary empty saddle is mostly seen after pituitary tumor surgery. Empty saddle needs to be distinguished from pituitary tumor remnants, pituitary tumor recurrence, and partially empty saddle combined with pituitary tumor.