Salt marsh,transitional area between land and sea with high primary productivity,provides habitat for many important species,and plays important roles in maintaining the function of wetland and global ecological balance.The structure and ecological functions of salt marsh are greatly influenced by climate changes and human activities.Hydrological connectivity of tidal channel is a key ecological process for coastal wetlands,and is important for maintainence and repairment.In the present work,we investigated a typical tidal channel system with major and minor tributaries in the Yellow River Delta.Characteristics of hydrological connectivity and distribution of soil and biological characteristics under different gradients of hydrological connectivity were analyzed.Intensity of hydrological connectivity was found to be affected by the shape of tidal channel and topography.The frequency of flooding and cumulative duration of flooding was found to be significantly correlated with topography and shape of tidal channel.Soil moisture content and salinity were affected significantly by strength of hydrological connectivity.Moisture content in spring tide was greater than neap tide.Area of high flooding frequency was greater than low frequency.Soil salinity was found to be greatly influenced by flooding frequency.More frequent flooding helps alleviate salinity stress.Distribution of Suaeda salsa biomass along gradient of hydrological connectivity was consistent with seed flow and density of soil seed bank,high frequency flooding area was greater than low frequency flooding area.It is concluded that Suaeda salsa distribution mainly depends on adaptability of plant life cycle to features of hydrological connectivity.