Objective · To make clear the role of cerebral microbleeds (CMBs) for early cognitive impairment in small vessel disease (SVD).  Methods · Fifty-seven consecutive SVD patients without dementia were strictly recruited. All participants were examined with a comprehensive battery of neuropsychological tests, SWI and DTI. According to the amount of CMBs, the patients were divided into CMBs group and non-CMBs group, or divided into multiple CMBs group (CMBs ≥ 3) and non-multiple CMBs group (CMBs<3). The mean diffusivity (MD) and fractional anisotropy (FA) in periventricular, central semiovale and subcortical white matter was analyzed with a region-of-interest method.  Results · The score of multiple CMBs group in attention and memory function was significantly lower than that of the non-multiple CMBs group. Correlation analysis showed that the count of CMBs in the whole brain was significantly correlated with periventricular white matter MD, subcortical white matter MD, periventricular white matter FA and subcortical white matter FA. The count of CMBs in the whole brain adjusted by age, gender, education was significantly correlated with attention/ executive function. After adjustment of subcortical/ periventricular white matter FA and MD and locations of CMBs they still had significant correlation.  Conclusion · CMBs can reflect the degree of destruction of white matter integrity, and have independent effects on injury of brain parenchyma, resulting in early cognitive impairment. The research also suggests the role of CMBs in cognitive impairment may exist threshold value effect.