Objective To investigate the application value of diffusion tensor imaging (DTI) combined with diffusion-weighted imaging (DWI) in the diagnosis of acute cerebral infarction (ACI) ischemic penumbra (IP). Methods Seventy patients with ACI who underwent magnetic resonance DWI and DTI scans were divided into hyperacute (6h) group and acute (6-24h) group according to the onset time. The apparent diffusion coefficient (ADC) values, anisotropic indexes (FA) and average diffusion coefficients (DCavg) of core infarction area and IP area, the rADC value, rFA value and rDCavg value of the contralateral side were statistically analyzed. Results ADC values, FA values and DCavg values of the core infarction area in patients with ACI were significantly lower than those in the contralateral area (P＜0.05). The ADC values, FA values and DCavg values of the IP area were significantly higher than those in the core infarction area (P＜0.05). The ADC value, FA value and DCavg value of the cerebral infarction IP area were lower than those of the contralateral side. The rADC value, rFA value and rDCavg value in acute stage were significantly lower than those in hyperacute stage (P＜0.05). The rADC value was positively correlated with the rFA value and rDCavg value (r=0.589, 0.685, P＜0.05), and the rFA value was positively correlated with the rDCavg value (r=0.612, P＜0.05). Conclusion The ADC value obtained by MR-DWI and the FA value and DCavg value obtained by DTI may be an important means to determine IP.