Based on the numerical simulation technique of unsteady flow,an applied mathema-tical model has been established to compute the tidal currents in the tidal river network of the downstream areas of the Sheyang River Basin. The model is mainly the node-channel model and can be applied in water quantity computation for large-scale complex river networks in plain areas. The computational results show that the model can pre-cisely simulate the tidal currents.On the basis. of successful simulation of the tidal currents that happened in the past, the model has also been applied to predict the tidal current changes in the case of sea level rise. The predicted results show that:(1)If the sea level rises,the water level and tidal level of each river will also rise.(2)The average high tidal level just down Sheyang and Huangsha sluice gates will rise approximately as much as the value of sea level rise,while the rising scope of the av-erage low tidal level will be smaller than that of sea level,thus the tidal range will in-crease.(3)The discharge capacity of all rivers which connect with the Yellow Sea will de-crease obviously.At last,the author analyses the changes of the flood/waterlogging disasters if the 1991 flood meets with future sea level rise, and puts forward some countermeasures about disaster reduction and prevention.