Aiming to reasonably demonstrate the downward mining feasibility of the bottom coal seam under the repeated mining in close multiple coal seams, a study of the failure characteristics and downward mining feasibility was conducted based on Qianjiaying coal mine of close multiple coal mine with downward mining using theoretical analysis, numerical simulation, and on-site detection. Based on the theory of slip line field in coal seam mining floor, the failure depths of the floor were 7.85 m and 4.18 m after the initial and repeated mining of upper coal seams, by optimizing the stress zone of the abutment pressure in front of the coal wall. The bottom coal seam was not affected and maintained good continuity and integrity. The numerical simulation results showed that the fracture number in the floor increased under the influence of the initial and repeated mining of upper coal seams, but the development of fracture depth remained basically unchanged. The fractures were densely developed to the main roof of the bottom coal seam. The GPR on-site detection results showed that the electromagnetic signal distribution of the floor was relatively uniform after the initial and repeated mining of upper coal seams, and there were no abnormal phenomena such as large-scale fluctuations of electromagnetic signals. The roof of the No.9 coal seam can be maintained integrity with good mining feasibility.