The top-coal falling ability is a key factor to analyze for the application of coal mining with top-coal caving.Based on a hard-and-thick strata, which acts both as the floor of the upper coal seam and as the roof of the lower coal seam, nine mining projects were put forward to examine the mining of upper and lower coal seams, and a numerical simulation was used to study in detail the corresponding top-coal compressed volume of the lower coal seam. By the simulation effects of different layouts of coalface, the rational mining method was determined to be the staggered layout of coalface in the upper and the lower coal seam. This can ensure the successful use of fully-mechanized coalface with top-coal caving in the lower coal seam.