Based on mine roadway roof fall accident protection problem，the common compound roof caving accident type was analyzed，then the mechanical characteristics of caving accidents and deflection separation were studied，and the discrete element analysis software using UDEC to simulate the caving process of composite roof， the composite roof caving accident prevention measures were discussed，and the scheme for joint bolt composite roof supporting was put forward. The research content of this paper has positive guiding significance for the management of compound roof of roadway and the protection of roof fall accident.