Abstract: River habitat connectivity is very important for the quality and stability of river water ecosystem, and is the key to river ecological recovery and health protection. How to quantify the impact of the dam site on river habitat connectivity is of great significance for water ecological protection and restoration. In this study, North Canal River, a typical multi-dam river in northern China, is selected as the research object, and the influence of dams on river habitat connectivity is quantitatively analyzed by Dendritic Connectivity Index（DCI）.The relationship between the number of dam space, the length of dam cut section, the length of total river length and DCI value in the basin in 1980, 2000 and 2020 shows that the number of dams in different periods was 11, 20 and 23, with DCI values of 51.6, 28.7 and 26.5, respectively.During the 40 years from 1980 to 2020, the number of dams increased by 109.1%, while DCI decreased by 48.6%, reflecting the deterioration of river habitat connectivity. The results also show that the impacts of dams in different spatial locations on river habitat connectivity are different, which shows that the dams in the main stream have more impact on river habitat connectivity than those in tributaries. The simulation results show that the average impact of dams in the main stream of the North Canal River is about 10 times that of the tributaries. The fish species and quantity survey also show that the increase in the number of dams in the North Canal River has a significant negative impact on the river habitat connectivity. In this paper, the analysis of habitat connectivity guarantee of river basin by increasing the DCI value of dam has certain guiding significance for ecological recovery, protection and restoration of multi-dam rivers.