The discharge curve Q=f (H) is a complex characteristic of run-of-river mode, which takes into consideration both: peculiar properties of the river bed and peculiar properties of the riverbed-forming activity. The discharge curve Q=f (H) is on the one hand the basis for the transition from levels to discharges and calculation with the help of them of all flow characteristics, on the other hand a kind of integral characteristic of the river channel mode. This article deals with the actual issue of constructing a curve, establishing relation between discharges and levels for shots of rivers when there aren't or there are few hydrological field observations. The article analyses the peculiarities of the hydrological and run-of-river mode of Russian rivers and are defined the generalized characteristics for construction of discharge curves. The relation of the generalized indicator alpha F/alpha M with the type of river channel regime is established.