Abstract: Bedding slope is formed in the excavation of cutting slope during construction of Lanzhou-Yongjing Highway, with K23+520 large bedding landslide being the most typical. Due to the importance of shear strength parameters of rock and soil in the slope stability and support design, in order to better realize the reinforcement design and stability analysis of similar slopes, taking K23+520 section of landslide as the research object, a method is put forward to determine the shear strength parameters of slip surface of bedding landslide with weak interlayer: for the landslide with a given location of slip surface, the failure conditions of the bedding landslide (critical height, local stability coefficient) and the deformation characteristic are combined to revise muttiple groups of strength shear parameters to meet the rigid sliding model step by step, the strength parameters satisfying the requirements of engineering application are obtained, and the results are used for the reinforcement design and stability analysis of similar slopes. This method is suitable for determining the strength parameters of the structural plane of K23+520 bedding landslide of Lanzhou-Yongjing Highway and other similar landslides, and it has a certain practical value in engineering.