Abstract: The river and tidal dynamics in the Pearl River Delta（PRD）are disturbed by strong human activities and changes different from the natural evolution. To explore the evolution of river and tidal dynamic characteristics in the river network of the PRD in recent years,based on the hourly water level and discharge data of two floods in the PRD,“99.7”and“17.7”,this paper adopts the Fourier transform method to obtain the residual water level（low frequency）and tidal（high frequency）components in the water level time series for comparative analysis. The results show that the relation curves of residual water level and discharge at Makou and Sanshui stations move down,with lower residual water level at the same discharge;whereas the residual water levels near the lower mouth of the PRD rise slightly,making the decrease in the residual water level slope;the increase in water depth results in the decrease in the resistance of tidal propagation,which leads to the attenuation rate of tidal range also decreases accordingly. The riverbed down-cutting caused by reservoir construction and waterway regulation is the main reason for the change of river and tidal dynamics of the PRD in recent years.