In this paper, the erosion-resisting coefficient is introduced to compute bed deformation in a crush bedrock river. In the case of crush bedrock, there is no proper control equation to describe bed stability, which leads to difficulty in calculation of the bed deformation through conventional method. The data from field survey are used to generalize the erosion-resisting capability where erosion-resisting coefficient describes. After the determination of longitudinal distribution expressed by polynomial regression and transversal distribution expressed by normal distribution function, the plane distribution of erosion-resisting coefficient in a crush bedrock river is obtained. With the computational results from horizontal 2-D flow mathematical model, erosion-resisting coefficient and controlling condition of local stability are employed to compute the values of bed deformation when riverbed is stable. The above method is applied in a case study, and the computational results of flow and bed deformations are in good agreement with physical model test data.