Objective To explore the occult damage of normal appearing white matter (NAWM) in patients with small vessel disease(cSVD) by using diffusion tensor imaging (DTI)technology, and its relationship with cognitive impairment. Methods Twentythree patients with cSVD and thirteen matched volunteers all received conventional MR scanning, DTI and montperllier cognitive function scale (MoCA) examination. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were measured symmetrically and compared among the two groups. Pearsoncorrelation analysis was used to determine the correlation between the FA，ADC and MoCA score in cSVD group. Results FA value on bilateral frontal and apical NAWM in cSVD group were lower than control group, and ADC value were higher than control group.The decreased FA value on bilateral centrum semiovale was demonstrated in cSVD group. FA value on bilateral frontal lobe decreased obviously, right (0.354±0.051)vs(0.398±0.027), P=0.01, left (0.365±0.053)vs(0.405±0.035),P=0.00).In cSVD group, the FA value of bilateral frontal NAWM were positively correlated with MoCA score (right: r=0.43, P=0.01, left: r=0.50, P=0.02), and the ADC value of bilateral frontal NAWM were negatively correlated with MoCA score(right: r=-0.40, P=0.03, left: r=-0.37, P=0.00). Conclusion The occult damage of normal appearing white matter (NAWM) can be detected using DTI. And DTI can reflect the severity of cognitive impairment in patients with cSVD.