At present, there are still some limitations in the process of mining and construction of the end slope of the near-horizontal composite coal seam open-pit mine. Only the mining of the lower coal seam is studied, and the mining of the top coal seam is more difficult and less studied. Therefore, in order to carry out the mining of the top coal seam in the near-horizontal composite coal seam, the author analyzes the engineering geological condi-tions and strata occurrence characteristics of the slope of the Baorixile open-pit mine, and uses FLAC3D to con-struct the three-dimensional numerical simulation model of the end slope, and calculates the relationship between the filling step distance and the slope stability when the top coal seam 1-2 is mined with the help of the inner dump plate. The slope stability control technology and corresponding mining scheme of 1-2 coal seam in top coal seam are determined. The research results show that the replacement step distance of the top-level coal seam in the end-slope 1-2 coal seam is not more than 80 m. When the top-level coal seam in the end-slope 1-2 coal seam is mined, the equipment is arranged on the flat plate of the inner dump developed to the bottom plate of the 1-2 coal seam. The mining method is layered tamping and inner row tracking backfilling. The whole region can recover 1-2 coal 22.6 million t by end slope mining, and obtain income of 4.972 billion yuan.