Abstract: According to a form optimized problem of a soft rock reversed dip slope in a composite seam, with a north highwall slope of Zhaha Naoer Surface Coal Mine as an engineering background, based on a rigid limit equilibrium theory, with a mining method with a crosscut and in pit dumping, from an analysis view of a 2D sI ope stability, a level after level optimized method of the composition seam slope was provided and a slope parameter of north highwall boundary of Zhaha Naoer Surfac e Coal Mine was determined. A FLAC3D numerical simulation software was applied to analyze the slope stability and the landslide mechanism of the north highwall after the optimization. The results showed that with the time effect occurred by the mining method with the crosscut and in pit dumping on the slope, the stability parameters of the slope in the different layer of the north highwall in Zhaha Naoer Surface Coal Mine were finally determined as 1.20, 1.10 and 1 .05 individually from top to bottom. After the level after level optimization, the completed slope angle of the north highwall was increased to 29°, the mining slope angle of the deep steep highwall was incr eased to 34° and the cause mechanism type of the landslide mechanism was a pushing type. The main failure mode of the slope rock mass was a tensile-shear compos ition type.