Abstract: In response to the serious problem of the bottom heave of the soft rock mining roadway in Mindong No. 1 Mine，mineral composition analysis, numerical simulation and on-site monitoring methods are used to analyze the deformation and failure laws of the floor under the influence of mining, reveal the mechanism of the floor heave phenomenon in the roadway, and propose reasonable control countermeasures. The research results show that: (1) the floor contains a large amount of mineral components such as illite and montmorillonite that are easy to swell in contact with water, and the floor is a water-swellable bottom heave; (2) the closer the roadway is to the working surface, the more severe the impact of mining, The damage of the bottom plate becomes more and more serious, and the bottom plate bulges under the action of the higher stress of the two sides; (3) The type of the bottom drum of the 06 working face transportation along the trough is water swelling + mining-induced squeezing fluidity composite bottom drum. Therefore, according to the bottom heave law and the bottom heave mechanism of the 06 working face along the trough, the over-excavated bolt reinforcement backfill support proposal is put forward.