Abstract: Taking the extra thick coal seam in Jindi Mine project as the background, using the finite element software FLAC^3D and actual measurement analysis to study the influence of pretention force on the stability of roadway support structure properties in thick coal seam. The research shows that the increase of bolt pretention force can effectively reduce the layers separation of shallow roof surrounding rock, and the increase of cable anchor pretention force can make couple between shallow roof supporting beam and deep supporting arch; exerting a reasonable cable anchor pretention force can improve the bearing capacity of the composite beam by 113.74%; for extra thick coal seam roadway, the reasonable value of the bolt pretention force is 60 kN, and the cable anchor is 150 kN; when the pretention force is too small, it can not be formed a stable bearing structure above the roof; when the pretention force is too large, it is easy to cause bolt and cable anchor failure or damage. The application shows that reasonable pretension force can make the roadway support structure stable and have a good support results.