Abstract: According to the serious deformation problem of soft bottom gob-side entry retaining in the fully mechanized caving face, taking the S1303 auxiliary air intake trough in Gucheng Coal Mine as the research object, and using the methods of on-site investigation, numerical simulation and field test, the paper analyzes the soft bottom edge of the fully mechanized caving face. The abnormal deformation characteristics of gob-side entry retention are studied, and the stress change law of soft-bottom gob-side entry retention in long-mechanized caving face is simulated and studied. The simulation results show that there is a stress peak at about 7.5m away from the solid coal, so as to determine the relevant parameters of the segmented hole reaming technology; And put forward the coordinated control technology of surrounding rock zone with the core idea of "controlling the top - limiting the help - letting the bottom" as the core idea; through the industrial test results, it is believed that this technology has a better supporting effect, improves the overall stability of the gob-side entry retaining, and can achieve efficient treatment of weak coal seam floors. Gob-side entry retaining with soft bottom under similar conditions has certain reference significance.