Along with the exploitation of tidal flat and beach resources and the construction of water projects in the estuary region of the Pearl River, the estuarine boundary shape and dynamic environment changed greatly, which inevitably gave rise to the adjustment of estuarine riverbed morphology, exerting far-reaching influence on the stability of tidal estuaries. On the basis of stability analysis for the tide channel of Pearl River estuary, the hydraulic-geometric relation and the tide control indicator were put forward. Moreover, the relationship between entrance section area and average ebb flow for many years of the Pearl River estuary was established. The balanced section’s hydraulic-geometric relation was also established. On this basis, scouring and silting at the entrance caused by estuarine tide changes was forecasted. According to the relationship between riverbed sediment adjustment and flood discharge capacity change, we concluded that the ebb flow change at the entrance of the estuary should be controlled in 1%-2%. The research result provides quantitative reference for the management of water projects at the estuary.