Abstract: The loess-paleosol layer is interphase with large thickness as well as long deposition age. Because of compacted and cemented effects, the shear strength of soil increases with the buried depth. And the stratigraphic division and their parameters are difficult to be decided. The variation regularity of the shear strength parameters of the loess and paleosol with the buried depth are explored, and it is found that the cohesion of loess increases linearly with buried depth and the intercept is 0. The cohesion of paleosol increases linearly with buried depth, with a intercept of 50.5kPa and a slope close to that of loess. As for the internal friction angles of loess and paleosol, neither of them significantly changes with the buried depth. Based on the results of absolute sedimentation dating of loess-paleosol, the linear equations of cohesion and depositional age are further established. Using the advantage of FEM division, the cohesive linear increasing model and elastic-plastic FEM are combined to establish a FEM model of cohesive linear increasing with deposition age. Meanwhile, the strength parameters of loess and paleosol layers are assigned differently, and the strength reduction method is used to calculate the slope safety factor. The model is validated by the case of the Jijia landslide in Shanxi province, and the model rationality is proved.