A calculation model of composite soil layer slope with double weak intercalations is constructed based on the limit balance theory to explore the variation law of slope factor of safety under different weak intercalation parameters. The thickness of weak intercalations close to the surface (upper layer), the thickness of weak intercalations far from the surface (lower layer), gravity, cohesion, and internal friction angle are selected as factors of slope stability, and relevant orthogonal tests are designed. The research results indicate that the sensitivity of the above five parameters to slope stability is in descending order, internal friction angle, cohesion, gravity, thickness of upper weak interlayer, and thickness of lower weak interlayer. The greater the cohesion and internal friction angle of the weak interlayer in a certain range, the smaller its weight and thickness, and the more stable the slope. According to the specific geological conditions of the slope, use retaining wall or anti-slide pile to prevent the slope, pay attention to drainage problems and prevention measures.