Abstract: Configuration of river is closely related with hydrodynamic structures of flows, for the shape of a channel influences the flow structures in it, and the flow structures also affect the developing trend of the channel through the movement of sediment, forming a pair of dialectical interactions in the river system. The natural rivers are different in configurations, which can generally be divided into such types as straight, bending, branching and wandering. Among them, the bending river or the river composed of several curved channels, the result configuration of interaction between the natural river and the complex hydrodynamic flow structure in it, become one of the most important types in the study of river dynamics. As the basis of theoretical research, the establishment of model and the study on flows within a moving channel has become the focus not only from researchers of fluid mechanics, but also from investigators of river dynamics. Therefore, this study first established a theoretic model on the flow in a meandering channel with a moving boundary by using a streamwise-transverse coordinate system. It next discussed the hydro-dynamic instability characteristics of the laminar flow within the sine-generated moving boundaries. Then it quantitatively analyzed the influences of various character parameters to the velocity distributions of main flow. Finally, it obtained the selective influences from the curvature and meandering properties to the flow structure.