Abstract: According to the voussior beam theory, the main roof applies a given deformation on the surrounding rock of roadway driving along next goaf in sublevel caving face. The deformation mechanism of surrounding rock is analyzed by the energy principle,and the mechanical model of roadway roof coal is established. The mechanical problem of the roadway roof coal under a given deformation is solved by the variation approach, and the relationship among the subsidence of the roadway roof coal, the support resistance, the height and elastic modulus of roof coal,and the width of the roadway are further discussed.