Abstract: Aiming at problems existing in hydrology standard for navigation engineering of tidal reach, especially difference and junction of confirmation of the design water level and research of flow and sediment for seaport and inland navigation engineering, studying on demarcation and connection of hydrology standard of tidal reach was performed. Through expounding the basic features of the tidal reach, hydrology factors of all kinds of navigation engineering were analyzed. Then, the ratio of two characteristic values that are annual average of in-year variation amplitude of monthly average water level and annual average of tidal range, was presented as a dividing index of different sections in the tidal reach. By means of case study and calculation, demarcation and connection of the hydrology standard of two kinds of engineering was demonstrated. The result shows that the ratio reflects the influence of runoff and tide to hydrology condition in different sections. The hydrology standard of two kinds of engineering in tidal reach can be divided and connected preferably according to its different value.