Abstract: Objective To analyze the relationship between MRI imaging manifestations and pathological results of patients with primary brain lymphoma, and improve the accuracy of preoperative imaging diagnosis of this disease. Methods MRI imaging findings of 39 lesions confirmed by surgery and pathology in our hospital were retrospectively analyzed, and its relationship with pathology was also analyzed. Results There were 23 patients with single lesion and 16 patients with multiple lesions. A total of 79 lesions were found with 68 lesions located at supratentorial region and 11 lesions located at infratentorial region, 33 lesions were seen located in the deep alba, 15 lesions located in the basal ganglion, 8 lesions located in the callosum corpus 7 lesions located in the gray matter, and 5 cased located in the thalamus. Of the 79 lesions, 47 lesions showed isointensity signal, 32 lesions showed slightly hypointensity signal on T1WI. On T2WI, 54 lesions showed isointensity signal and 25 lesions showed hyperintensity signal. After Gd-DTPA injection, the lesions showed homogeneous enhancement mass in 25 lesions, heterogeneous enhancement mass in 8 lesions, nodular enhancement in 29 lesions, irregular enhancement in 9 lesions and enhancement like butterfly wing in 8 lesions. Clench fist sign were found in 15 lesions, angular sign in 26 lesions, incision sign in 28 lesions, and 3 lesions had adjacent dural enhancement. Slight para-tumorous edema was found in 33 lesions moderate edema in 29 lesions and marked edema in 17 lesions. Conclusion On MRI, primary brain lymphoma demonstrate similar signals with gray matter. Its pathological basis are closely packed tumor cells, high nucleoplasm ratio, little water in intercellular space, and tumor infiltrative growth surrounding blood vessels which damages blood-brain barrier, and it shows obvious homogeneous enhancement because of rare cystic necrosis.?