Abstract: In order to reveal the failure mechanism of cracked thick coal seam roadways with ultra large section and effectively control its surrounding rock, the Win kler elastic foundation beam theory was applied to establish the elastic foundation beam mechanical model of roadway roof. Besides, characteristic function formula of t he subsidence of coal roadway roof and roof rock beam moment was obtained. In addition, the variation relationship between roof subsidence and roof rock beam mom ent was analyzed, and was applied in Dongpo Mine. The field practice showed that when the new type of pre- stressed truss anchor cable support system was used. On the basis of this calculation result of the model, the surrounding rock control problem of cracked thick coal seam roadways was effectively solved, and the practice resul t proved the rationality of the model.