Hydrological connectivity has significant effects on the functions of estuarine wetland ecosystem.This study aimed to exam-ine the dynamics of hydrological connectivity and its impact on soil carbon pool in the Yellow River Delta,China.We calculated the hydrological connectivity based on the hydraulic resistance and graph theory,and measured soil total carbon and organic carbon under four different hydrological connectivity gradients( Ⅰ0-0.03,Ⅱ 0.03-0.06,Ⅲ 0.06-0.12,Ⅳ 0.12-0.39).The results showed that hydro-logical connectivity increased in the north shore of the Yellow River and the south tidal flat from 2007 to 2018,which concentrated in the mainstream of the Yellow River and the tidal creek.High hydrological connectivity was maintained in the wetland restoration area.The soil total carbon storage and organic carbon storage significantly increased with increasing hydrological connectivity from I to III gradient and decreased in Ⅳ gradient.The highest soil total carbon storage of 0-30 cm depth was 5172.34 g/m2,and organic carbon storage 2764.31 g/m2 in Ⅲ gradient.The hydrological connectivity changed with temporal and spatial change during 2007-2018 and had a noticeable impact on soil carbon storage in the Yellow River Delta.The results indicated that appropriate hydrological connectiv-ity,i.e.0.08,could effectively promote soil carbon storage.