Abstract: On the basis of summarizing empirical formula of coal floor failure depth in our country, comprehensive consideration and utilization of seam depth, dip, seam thickness, face length, floor damage and the extent of damage and other factors, taking the actual mining of a mine face as the background, we analyze coal floor mining characteristics by UDEC numerical simulation, which reveals failure characteristics and failure depth of floor seam mining process, and comparatively verifies the accuracy of floor failure depth empirical formula.