Abstract: Based on the concept of the numerical dispersion of Kinematic-wave to model the physical dispersion of diffusion wave at a certain condition,the Muskingum-Gunge flood routing method is developed by means of the finite difference method.As for the weighting factor X in the method,hydrologists have not obtained a uniform conclusion for along time,so this paper researches the problem using the Von Neumann and the stability condition of the routing method is systematically analyzed.