Objective To investigate the value of diffusion tensor imaging in acute cerebral infarction and motor function evaluation. Methods MRI features were analyzed in 49 patients in acute cerebral infarction with different timing. All patients underwent conventional MRI, DWI and DTT scanning. The FA value and ADC value were measured and reconstruct the corticospinal tract by DTT. Results In acute cerebral infarction, FA value continued to decline after the oneset of attack, and ADC value showed an upward trend. Difference of FA value and ADC value between the central and peripheral regions were significant in hyperacute and acute stroke. According to diffusion tensor fiber tractography (DTT) and based on the relationship between infarction and corticospinal tract, divided into not compression, compression without interruption(the compression group), disruption and decreases(the destruction groups).There has statically significant difference between two groups in FA, ADC value and NIHSS score. Conclusion Magnetic resonance diffusion tensor imaging in the acute cerebral infarction with FA and ADC value have characteristic discipline, can be assessed the ischemic penumbra. DTT can show the relationship between infarction and corticospinal tract has important value to prognosis.