The association between the glymphatic dysfunction and cerebral small vessel disease (SVD) is still unclear due a lack of in vivo measures. In this work, we employed a novel method based on the coupling between global blood-oxygen-level-dependent (gBOLD) signal and cerebrospinal fluid (CSF) inflow, which could detect alterations in CSF dynamics. We found that patients with severe SVD had significantly impaired glymphatic function. The dilation of peri-vascular space and the presence of diabetes were associated with worse glymphatic function. These results may provide useful knowledge for understanding the mechanism of SVD and improving clinical treatment.