Abstract: Rainfall is an important cause of deposit slope instability in engineering area. How to evaluate the influence of saturated-unsaturated seepage flow on the stability of deposit slope under rainfall condition? The challenge lies in accurately obtaining the unsaturated seepage parameters of deposit body. Taking Meijiatai landslide control project as the research object, unsaturated hydraulic parameters and boundary water level are obtained by using saturated-unsaturated finite element analysis and dynamic inversion of seepage field based on monitoring data, and then limit equilibrium method is used to analyze the change of landslide stability. The results show that the groundwater level at the back edge of the slope changes dynamically from 692.0 m to 694.5 m, and the groundwater level in the slope varies from 3.0 m to 12.0 m under the influence of the back edge recharge and rainfall infiltration. After the drainage measures were implemented, the groundwater level decreased by 9.0 m, and the variation amplitude was reduced to 1.0～5.5 m. At the same time, the range of the transient saturation area of the weak accumulation zone in the middle of the landslide was reduced by 84.5%, and the saturated area at the foot of the slope was suppressed below Highway 1, which played a great role in drainage and pressure reduction. There are three instability modes of landslide: shallow slide along the central weak zone, shallow slide along the lower front, and cut out from Highway 1 along the old slide zone. The stability decreases significantly during rainfall infiltration, and the stability coefficient decreases to 0.82, 0.99, and 0.98 respectively, which is less than the stability safety coefficient of 1.05. Under comprehensive management measures, the stability coefficients are increased by 0.28, 0.13 and 0.19 respectively, and the current stability coefficients are 1.10, 1.12 and 1.17 respectively. The stability coefficients of each instability mode are greater than the stability safety coefficient, and the landslide is in a stable state. The research results can provide reference for similar engineering management design and seepage stability analysis.