Abstract: The security and stability of Yangtze River embankment is an important matter that has been paid close attention to by national leader. In this paper the geologic condition of representative dyke in the middle and lower reaches of Yangtze River is introduced, which includes geographical position, hydrometeorology, topography and physiognomy, geological structure, stratum lithology and dyke matter and so on. The stability analysis of the dyke is discussed. Numerical examples show that dyke is steadier the days of river water level rising or keeping than the days of the dyke being nature. The safety factor of embankment stability drop suddenly when the water level falls rapidly, and landslide will happen in all probability.Of all the parameters of elastic modulus, Poisson's ratio and mass density the most sensitive parameter for the embankment stability is mass density, and modulus of elasticity is the smallest sensitive one. For the intension indexes of cohesion c and friction angle φ on the gliding surface, it is common sense that the influence of φ to the safety factor is much more remarkable than that c. In fact, it is conditional. That is correct if the depth of landslide is large, but the influence of c to the safety factor enhances obviously if the depth of landslide is small. So the parameter c should be paid more attention for a shallow landslide.