Soil strength anisotropy and seepage are important factors affecting the stability of slopes. In order to make the anisotropy of slope soil strength more practical in stability calculation, a method of graded loading and zoning of layered slope soil considering strength anisotropy is proposed, that is: firstly, the initial zoning is established according to the size distribution of the maximum principal stress direction angle of the slope soil and the intersection area of layered soil, and then, combined with the finite element calculation results, the formula for calculating the anisotropy strength parameter of each layered soil is derived and the strength parameter of each zoning is calculated instantly; secondly, the strength parameter of the soil in each zoning is further adjusted according to the calculated strength parameter during the process of applying load step by step. Secondly, in the process of applying load step by step, the initial partition is further adjusted according to the calculated soil strength parameters, and the partition and the corresponding strength parameters of the coupling calculation are determined through the three-level control of initial partition, subdivision and fine partition. On this basis, a flow-structure coupling model considering three working conditions: zoned anisotropy, unzoned anisotropy and unzoned isotropy of the soil body is established, and the change rules and characteristics of the stress field, displacement field and seepage field of the slope body are analyzed, and the stability of the slope is calculated using the strength reduction method. The results show that the average stress maximum value of zoned anisotropy is lower than that of unzoned anisotropy, but higher than that of unzoned isotropy, and the seepage and flow velocities are lower than those of the other two cases; the calculated slope stability coefficient of zoned anisotropy is 1.109, which is 2.8% and 21.3% lower than those of the other two cases respectively.