Abstract: By the definition of bed forming discharge, sediment transports during flood tide and ebb tide of various tidal frequencies were calculated for a tidal estuary. The results show that the bed forming effects are the strongest at annual average runoff combined with mean ebb tide, so the bed forming discharge of this estuary should be the ebb-tide discharge. Tidal estuaries can be categorized as two types, namely general estuary and tidal bore estuary. The former's characteristics of cross section depends on average ebb-tide discharge and average sediment concentration, while for the latter, its width of cross section depends on average flood-tide discharge, and its corresponding depth, longitudinal widening rate and bed slope of river channel are determined by both flood-tide and ebb-tide discharges and sediment concentration. This paper formulates a series of empirical relationships between hydrodynamics and morphology for macro-tide estuaries. Using the measured cross-sectional bed profiles of five estuaries in Zhejiang province, we have verified these formulas of river regime, including cross-sectional area, width and depth, width-depth ratio, widening rate, expanding rate of cross-section area, river bed slope, etc. Their average calculation errors are less than 10%, and the calculations with errors exceeding 90% are less than 20%. The formulas, through certain conversion, show that the cross sections below half-tide levels correspond to the ones for sediment recipient motions.