Abstract: The stability control of the floor is the basis of the stability control of the ' support-surrounding rock ' system in steeply inclined coal seam mining. Based on the engineering background of a steeply inclined long-wall fully mechanized mining face in a mine, this paper adopts the research method of combining physical similarity simulation and numerical calculation. On the basis of comprehensively determining and analyzing the general law of asymmetric deformation and failure of floor, the transmission path of floor mining stress and its dip angle effect are studied, and the evolution characteristics of principal stress gradient and direction deflection of floor in steeply inclined stope are quantitatively characterized. The results show that in steeply inclined coal seam mining, the transmission path of mining-induced stress in the floor exhibits an asymmetric anticlinal shape under the influence of the coal seam dip angle. Within the stress arch, the immediate floor and the basic floor in the middle-lower region of the working face are under tensile stress, with the principal stress direction nearly parallel to the coal seam. Outside the stress arch, the principal stress in the floor deviates toward both sides of the coal body, with the stress deflection boundary serving as the demarcation line. Furthermore, as the coal seam dip angle increases, the arch height of the floor stress arch and the support pressure on the lower side of the working face floor exhibit a decrease-increase-decrease trend. The magnitude of the first principal stress and the unloading coefficient gradually decrease, with the maximum unloading position migrating toward the coal body on the lower side of the working face. The direction of the first principal stress gradually deflects towards the coal seam, resulting in a gradual reduction in the depth of floor failure. As a result, the maximum failure depth of the floor is located in the middle-lower region of the working face. Meanwhile, influenced by the unequal confinement effect of the goaf's waste rock, the floor block structure in the middle-upper region of the working face is more prone to instability and sliding, with upward expansion likely under continued mining disturbance. Based on these findings, targeted preventive measures such as "key monitoring and regional treatment" can be implemented in areas prone to failure and sliding. These measures aim to improve the stress environment and structural characteristics of the floor in these regions, thereby achieving effective stability control of the floor in steeply inclined longwall mining faces.