Objective To investigate the application value of magnetic resonance diffusion tensor imaging (DTI) in evaluating the effect of motor function rehabilitation in patients with cerebral infarction. Methods Magnetic resonance imaging (MRI) and DTI examination were performed in 36 cases of patients with chronic cerebral infarction in the hospital before and after the motor function rehabilitation. The image data were processed to obtain fractional anisotropy (FA) pseudo color pictures. The bilateral corticospinal tract (CST) reconstruction was performed and the related data of contralateral healthy side and diseased side were statistically analyzed. Results Among the 36 patients, 15 cases were in grade 2, accounting for 41.67% and 21 cases in grade 3, accounting for 58.33%. 15 cases in grade 2 were taken as group A while 21 cases in grade 3 as group B. The rehabilitation FA value in group A was (0.612±0.039) which was significantly higher than that in group B. After recovery, that in the two groups decreased significantly. Compared with that before recovery, the difference was significant (P＜0.05). After recovery, the FA value in group A was (0.556±0.064) which was significantly higher than that in group B, which was statistically significant (P＜0.05). Before recovery, the Fudl-Meyer score in group A were (85.162±9.861) points which were significantly higher than those in group B, and the difference was significant (P＜0.05). The decreasing percentage of CST FA before and after rehabilitation was negatively correlated with increasing percentage of Fudl-Meyer score. Conclusion Magnetic resonance DTI technique can be used to evaluate the effect of limb motor rehabilitation training according to the extent of CST damage.