Objective To evaluate the relationship between preoperative MRI characteristics and the perioperative outcomes of microvascular decompression in primary trigeminal neuralgia. Methods To analyze the relationship between preoperative MRI characteristics and the perioperative outcomes in 103 primary trigeminal neuralgia patients with micro-vascular decompression in Nanfang Hospital. The MRI features such as the ratio of CPA area, TGN cross-sectional area and TGN length was evaluated together with the TGN oppression distance, the position of TGN, the position of basilar ar-tery and the type of offending vessel as well as the outocmes including complete disappearance, temporary remission and ineffectiveness. Results Univariate analysis showed that the oppression orientation (P=0.017), oppression distance (P<0.001), offending vascular type (P=0.016), TGN cross-sectional area ratio (P<0.001) were the influencing factors of periop-erative outcomes. Logistic regression analysis showed that the offending vascular type (P=0.002)and TGN cross-sectional area ratio (P=0.020) were the main predictive factors of perioperative outcomes of microvascular decompression. Conclu-sions Preoperative thin slice MRI scanning showed that the offending artery, non-atrophy nerve roots, far distance from op-pression point to brainstem may be the favorable factors of perioperative outcomes of microvascular decompression.