Abstract: Computational river dynamics(CRD) has been developing very fast after the use of the numerical model during the past 50 years. It is of great significance to systematically organize the theory system of the CRD. CRD is mainly used to study the spatial and time variation of the river dynamics. The computational fluid dynamics(CFD),the computational soil mechanics(CSM) and the traditional river mechanics(TRM) are creatively used in CRD. But this is not simple or direct use. The main problem comes from the complex interaction in the multiphase and the multi-scale of the river system. Many new river dynamics model and the numerical technics are created in the processes that the problem is solved. However, all these technics are not systematically organized and analyzed. In this paper, all these theories are systematically organized and analyzed based on CFD and CSM. It is easily to decide the correction, complexity, application feasibility of the different models, which is helpful to choose the model when used in practice and decide the direction of development of the model.