Objective To investigate the preoperative magnetic resonance imaging (MRI) signal features of invasive pituitary tumors and their diagnostic value. Methods The clinical data of 55 patients with invasive pituitary tumors who were admitted to the hospital during the period from February 2015 to December 2017 were analyzed retrospectively. All patients underwent MRI scan and the maximum diameter of the tumor was measured. The shape, location, signal intensity, infiltration degree of surrounding tissues and the direction of tumors were recorded. Results MRI findings of invasive pituitary tumors showed slightly lower and equal signals on T1WI scan, and equal or slightly higher signals on T2WI. There were different degrees of invasion of surrounding tissue structure by pituitary tumors in 55 cases, showing different degrees of invasion of cavernous sinus, hourglass signs, collapse of sellar floor and thinning of bone resorption, etc. The coincidence rates of MRI in the diagnosis of invasion above and in the saddle was 100.00%, and in the diagnosis of cavernous sinus invasion was 90.00%. Conclusion MRI and dynamic contrast-enhanced scan can better display the size, location, growth direction of invasive pituitary adenoma and its relationship with surrounding tissues, and can guide the choice of surgical methods and prognosis.