The construction of large section chamber in the high-stress soft rock in the west is easy to cause the rapid, continuous and serious uplift of the floor, which causes the bending and folding of the floor and brings great challenges to the mine exploitation and mining transportation. Combined with the actual situation of horizontal door chamber in no. 18-2 roadway of Maiduishan Coal Mine and the typical geological characteristics of soft rock in the west, combined with the means of surrounding rock lithology analysis, ground pressure detection and indoor test, the formation mechanism of bottom heave in deep soft rock chamber was studied. According to the idea of coordination between active and passive support, a comprehensive control scheme of "primary masonry + anchor beam, anchor rod + secondary masonry" for the floor heave in soft rock adit was proposed. Numerical simulation and field monitoring show that the support measures can significantly improve the stress state of the floor, effectively improve the overall stability of the roadway, and significantly reduce the plastic failure area at the bottom. The chamber structure will enter a stable state in a short time, the uplift of the floor is only 60.5mm~74.5mm, and there is no obvious rheological phenomenon, the deformation inhibition effect is significant.