Abstract: The original mining process of Jinzhengtai open-pit coal mine was a single bucket truck process. Due to the significant defects of traditional excavation machines in terms of excavation depth and coal rock mixing, it has led to the problem of waste of overlying coal on the edge. Therefore, this article focuses on the coal pressure on the sides of the No.6,No.9 coal seams in the open-pit mine. A combined mining machine is designed to excavate and drop coal in each mining tunnel, while supporting a loading and operation system for coal transportation. Based on the stability parameters of the edge and the occurrence status of the coal seam, the mining parameters of the coal seam chamber, supporting coal pillars, and permanent protective coal pillars were calculated and designed. After calculation, the width of the mining chamber in the No.6 coal seam was determined to be 3.3m, the width of the coal pillar was determined to be 3.5m, the width of the mining chamber in the No.9 coal seam was determined to be 3.3m, and the width of the coal pillar was determined to be 4.1m; Leave a permanent coal pillar every 10 mining tunnels, with a width of 8.2m determined based on the width of the supporting coal pillar; After adopting the combined mining process of edge pressing coal, the coal resource extraction rate has been increased from 57.7% to 62.3%, the resource recovery rate has been increased by 4.6%, This has extended the service life of the mine and has high application and promotion value.