Abstract: The mechanism of river meandering is investigated experimentally based upon the principle of energy conservation.Our study reveals that meandering is a natural property of rivers.The curvatures of a river bend are largely controlled by the energy of river flow,i.e.,the flow rate and the channel slope.River meandering is a natural fluvial process to compensate the energy loss so that the river could keep itself moving forwards.The meandering channel process can result in a rise in the upstream water level,consequently increasing the potential energy in the channel reach and leading to a rising in the downstream channel slope as well as the kinetic energy increases.The latter,in turn,results in a relative equilibrium state between the flow and the sediment transport in the channel reach.The mechanism of river meandering may thus be rephrased as a river automatic regulating process.The degree of curvature in a channel reach is subject to the gained kinetic energy,i.e.,the difference in kinetic energy between upper-and downstream cross-sections determines the degree of river meandering.The automatic kinetic energy compensation in river reaches could be used as the mechanism to explaining river meandering.Such a mechanism is justified by the in-door experiments and field observation.