Abstract: Characterization of wetland hydrological connectivity is important to maintain and restore structure and function of wetland ecosystem．Sentinel-2 remote sensing images obtained monthly in 2019 were used to examine hydrological connectivity changes and frequency in the Yellow River Delta, and to analyze important patches using a graph theory-based landscape connectivity index．Hydrological connectivity in the Yellow River Delta was found to have undergone marked seasonal changes．Flood season and ecological water compensation were found to increase overall hydrological connectivity．Importance index distribution was found consistent with hydrological connectivity frequency．Patches with higher hydrological connectivity and frequency were found mainly distributed in recovery area on the south shore, in offshore tidal flats and main tidal ditches．These data would help ecological protection and restoration in the Yellow River Delta．