Reveal genetic relationships between hydrological processes and geomorphological process, to establish the quantitative relationship between the two, reached by topography parameters estimating hydrological characteristics of the process, reduce dependence on hydrological data is an important means to solve the hydrological data of the scarcity of small and medium rivers governance and mountain torrents disaster early warning and forecasting.The hypsometric curve is assumed to be the surface of the basin, and the curve of the steep degree reflects the slope of the basin's surface.To make things simpler and to generalize the results,assume the precipitation uniformly distributed over the basin and instrantaneously imposed upon it.The water drop velocity is related to the slope gradient, assuming that the time of the water drop on the slope reaches the outlet is determined by the slope and the distance.The hypsometric isochrone which is statistical curve, so that it is only suitable for the watershed which is in the stages of maturity, and the shape of the basin should be round.