Abstract: In view of the particular spatial structures and deformation shape induced by overlying strata during the coal exploitation process，roof mechanical model with three kinds of boundary support conditions of four edges clamped，two edges clamped and two edges simple supported，and four edges simple supported was built up by using the theory of small deflection of elastic thin plate.The analytic expression of roof deflection，bending moment and stress before and after fracturing of basic roof was obtained through theoretical calculation.Furthermore，the theoretical analysis on the roof breaking mechanism and behavior characteristics of roof fracture revealed the mechanical nature of stope roof with horizontal "O-X" shape fracture.The distribution rule and evolutionary characteristics of stress field in stope roof were studied by using three-dimensional numerical simulation software FLAC3D，where the simulation results are consistent with the theoretical analysis.

Key words: Theory of thin plate, Stope roof, Mechanical model, Theoretical calculation, Fracture characteristics