Abstract: Based on the analysis of influencing factors of floor heave in gob-side entry retaining, mechanical model of the floor in gob side entry retaining with large section was established.The left side of the beam (outside of backilling body) was simplified as a fixed hinge support, while the right side of the beam (under the limit e quilibrium zone of the coal side) was simplified as fixed end.The top surface and the bottom surface of the beam were applied loads from the backilling body, the coal s ide and the lower rock strata.Then, the floor deflection expression of gob-side entry retaining was established, which meets the displacement boundary conditions of flo or beam and was in accordance with the deformation characteristics of roadway in gob-side entry retaining.By using the principle of minimum potential energy, the defor mation of the floor beam in gob-side entry retaining was solved.Finally, the calculated result showed that the maximum deformation of the floor beam grows with increai ng of the thickness of the beam, and it was also increasing with the increase of the roadway width.According to the study on influencing factors and mechanical model 0 f the floor in gob-side entry retaining with large section, prevention and control technology of floor heave was put forward, then engineering practice of prevention and C ontrol of floor heave had been carried out, finally prevention and control direction of floor heave in gob-side entry retaining with large section was pointed out.