We correlated between the temporal chacteristics of the BOLD signals and venule structure at human primary visual cortex (V1). Functional MRI was measured by the high temporal resolution (100ms) simultaneous-multi-slice inverse imaging. Venule probability map was estimated from high spatial resolution (0.85mm) susceptibility-weighted imaging (SWI). Siginficant correlation was found between venule density and intra-/inter-subject temporal variability of the BOLD signal at V1. This correlation suggests that the temporal instability of BOLD signal is likely attributed to vascular structure or reactivity.