Objective To investigate the value of preoperative MRI imaging in the protection of pituitary function in endoscopic trans-sphenoidal pituitary adenoma resection. Methods The clinical data of 34 patients with pituitary adenoma who underwent elective endoscopic trans-sphenoidal pituitary adenoma resection were retrospectively analyzed. MRI examination was performed before and after surgery. Results In this group of 46 patients, 82.61% underwent total adenoma resection. Preoperative MRI showed that the adenomas were quasi-circular, lobulated and irregular, etc. MRI findings of pituitary macroadenoma showed equal signal on T1WI and high signal on T2WI and most of them had different degrees of enhancement; Pituitary microadenoma showed slightly low signal or equal signal on TI, equal signal or high signal on T2 and enhanced scan showed low signal. Soft matter mainly showed high signal and central and hard matter mainly showed low signal. Enhanced scan showed obvious enhancement. Postoperative MRI showed that the adenoma shadow disappeared, the contents of the saddle region significantly disappeared and high signals decreased significantly. 7d before and after operation, there were no significant changes in levels of GH, TSH, FSH and LH, without statistical significance (P＞0.05). Conclusion Preoperative MRI imaging has certain guiding significance in endoscopic trans-sphenoidal pituitary adenoma resection and can reduce the damage to the pituitary function.