Based on the condition of a fully-mechanized working face, two research means, i. e. microseismic monitoring and FLAC^3D numerical simulation, were introduced to study the formation and evolution of floor failure and water conducted pathways caused by coal mining. The space-time evolution law of microseismic rupture events was studied for the floor rock mass during the changing process of the mining stress field. The process of inoculation, development and penetration of potential water channels was also revealed under the condition of coal mining. Field microseismic monitoring shows that microseismic event accumulation is directly proportional to drilling footage. The number of microseismic events to some extent reflects the disturbance degree of mining activities on the floor rock. The distribution of microseismic events is intensive near the coal mining face, which shows that the floor rock mass is seriously damaged during coal mining. The greatest failure depth of the floor estimated from mine microseismic monitoring is 15 m. Numerical analysis indicates that due to mining disturbance effect, the rock stress around the mine stope is redistributed during coal mining. The abutment pressure increases in front of the coal mining face and the stress reduces in the mined areas. Stress concentration and release make contribution to the destroying of the floor rock. The maximum failure depth is up to 14 m calculated from numerical simulation.