Abstract: In order to study the sensibility of inclined coal seam floor failure depth factors, such as mining depth, mining height, working face length, coal seam dip angle and roof and floor lithological combination, to the depth of coal seam floor damage. Taking the stope conditions of Yangcheng Coal Mine as project background, the orthogonal simulation which is based on FLAC^3D numerical simulation software is made to the depth of coal seam floor damage at 1309 working face. Furthermore, this paper analyzes and researches the simulated result in the way of variance components method. Research shows that the order of each factor that influences floor damage depth is as follows: roof lithological combination, working face width, floor lithological combination, mining depth, mining height and coal seam dip angle. Roof lithological combination is the highly significant factor, and the significant factors include floor lithological combination, mining depth and mining height, while the unapparent factor is coal seam dip angle.