Objective To explore the clinical value of magnetic resonance perfusion weighted imaging (PWI) in middle cerebral artery (MCA) stenosis. Methods A total of 100 patients with unilateral MCA stenosis or occlusion who were admitted to the hospital from June 2016 to June 2018 were selected as subjects. They were examined with PWI after determining the degree of stenosis by digital subtraction angiography (DSA). Perfusion parameters of bilateral cerebral hemispheres, such as cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT) and time to peak (TTP), were analyzed statistically. Results DSA showed that there were 20 cases, 32 cases, 28 cases and 20 cases of mild, moderate, severe stenosis and occlusion, respectively. The detection rates of PWI were 85.00%, 93.75%, 96.43% and 100.00%, respectively. With the aggravation of stenosis, the abnormal perfusion rate of PWI increased significantly (P<0.05). Compared with the healthy side, except for mild stenosis, the CBF of the affected side was significantly decreased, and the MTT and TTP were significantly prolonged (P<0.05). With the aggravation of stenosis, the CBF on the affected side and the healthy side were significantly decreased, MTT and TTP were significantly prolonged (P<0.05). Pearson correlation analysis showed that the degree of MAC stenosis was negatively correlated with the ratio of CBF on healthy/affected side (P<0.05), and positively correlated with the ratio of MTT on healthy/affected side and the ratio of TTP on healthy/affected side (P<0.05). There was no correlation with the ratio of CBV on healthy/affected side (P>0.05). Conclusion Perfusion parameters are closely related to the degree of MCA stenosis. PWI examination can also reflect the hemodynamics of patients with MCA stenosis through changes in perfusion parameters, which helps to assess the establishment of collateral circulation in the diseased area and provides an objective basis for clinical intervention.