Objective This Paper is to study clinical value of magnetic resonance imaging diagnosis applied in transient ischemic attack. Methods Forty patients with transient ischemic attack were divided into two groups with 20 cases in each group according to the principle of randomized control, patients in the research group were subject to magnetic resonance diffusion imaging, patients in the control group were subject to conventional magnetic resonance imaging, and diagnosis results of patients in two groups were compared. Results The positive detection rate (90.00%) of patients in the research group during catabasis period (95.00%) were higher than those of patients in the control group (70.00%, 80.00%) (P<0.05), and the inter-group difference was significant. The detected lesions of patients in the research group were more than those of patients in the control group, the diameter of lesion in the research group were longer than that of patients in the control group, the inter-group comparison satisfied P<0.05, and the differences were significant. Conclusion Accurate diagnosis rate of magnetic resonance imaging is significantly higher than conventional magnetic resonance in diagnosis of transient ischemic attack, the accuracy of specifically damaged intracranial part is high, and the prospect of clinical application is wide.