Abstract: Due to impact loads resulting from lateral rotation and subsidence of the main roof in inclined coal seams, gob-side entry retaining exhibit severe surrounding rock deformation and failure, with particularly pronounced floor heave. This study addresses the engineering challenge of controlling large floor deformation in the gob-side entry retaining at the 1301S working face of a coal mine. Initially, based on “O-X” fracturing motion law of the main roof, according to D’Alembert’s principle and Rankine’s earth pressure theory, the dynamic model characterizing the lateral rotation and subsidence of the main roof was established, the stress of roadway floor under abutment pressure of inclined coal seam was analyzed, the failure mechanism of the roadway floor under the influence of the impact loads was elucidated, and mechanical instability criterion η for roadway floor failure wan established. Then, through numerical simulation, the failure characteristics of the floor before and after the impact load disturbance were explored, and the failure characteristics of the floor under the influence of different factors was analyzed. Finally, integrating strategies for both load source control and enhancement of load-bearing capacity, the floor heave control method is proposed. This methodology was implemented in the gob-side entry retaining of the 1301S working face. Key findings show: The lateral rotation and subsidence of the basic roof generated impact loads far exceeding the self-weight, and these loads, together with the extrusion pressure acting on the floor of the roadway, were superimposed, ultimately causing the large deformation of floor heave of the roadway. The impact load strength is positively correlated with the fracture length, height, bulk density and mining height of the main roof. Substitution of field-measured data into the mechanical instability criterion yielded η = 1.06 > 1, indicating floor buckling instability consistent with observed large-scale floor heave. The post-impact floor heave amount and failure depth increased significantly. With the decrease of the impact load strength and the increase of the bending stiffness of the floor, the maximum floor heave and the failure depth decreased. The failure process progresses of the floor sequentially through three distinct stages: initial slow deformation, followed by abrupt deformation, culminating in deformation stabilization. A combined control method of floor heave based on blasting roof cutting and floor layered grouting is proposed. The field monitoring results confirm that the floor heave of gob-side roadway retaining is effectively controlled, the maximum floor heave is reduced by 73.4%, and the overall stability of the surrounding rock is good.