Abstract: By simulating the complex mountain building slope in natural, storm and earthquake conditions, the research targeted how the properties of soft interlayer or anti-slide pile diameters affect the stability, and also investigated the plastic failure area distribution. The results show:(1)The stability has obviously promoted after the pit is backfilled, especially in the storm condition. (2)After the anti-slide pile reinforced the slope, the damage caused by earthquake is faintly. But the pile diameter is critical in the storm condition. (3)When the pile diameter is small, the anti-slide piles and anchor cable have reinforce the slope together. As the pile diameter increase, the anchor cable becomes ineffective. (4)Under a smaller angle, the plastic failure area is located in the soft interlayer by shear failure. When the angle takes the maximum, the failure area transfers to the shallow soil by tensile failure.