Abstract: In the mining process for extra thick coal seams with close range, rib spalling and floor heave of crossheading of coal seam beneath often happen. Based on this background, the methods of theoretical analysis and field monitoring were used to investigate the deformation and fracture behaviors of floor roadway. Fracture depth of floor of working face under the action of mining and influence sphere and extent that abutment pressure has on floor roadway were obtained. This research can provide some references for layout and support design of floor roadway under the effect of mining closed coal seam with extra thick.