Abstract：During cyclic weighting in fully-mechanized sublevel caving face，the stowing degree of the goaf influences the stability of hard and massive overlying roof. The course of top coal falling from begin to end is dynamic. To set up the judgment rules of roof stability with the top coal′s recovery ratio is an important theoretical problem. The mechanical model of the stability of the whole roof deformation and the part contact of the main roof is established. Based on the structure stability theory and the strength theory，two kinds of limited subsidence maintaining the stability of the whole deformation of roof structure and the stability of part contact of the main roof are gained. According to the comparison of the limited subsidence and the subsidence of roof brought about by the movement situation of roof in the course of rotation；the unified mechanical conditions between the stability of the whole transmutation of roof structure and the stability of part contact of the main roof are analyzed；and the judgment rules of roof stability with the top coal′s recovery ratio are established. Based on an example of fully-mechanized sublevel caving face，the judgment figure and method with the top coal′s recovery ratio are put forward；the theoretical bases of designing the safe top coal′s recovery ratio are provided according to different roofs，and the safe roof controlling is achieved at coal mine.
