Abstract: Rock burst occurring in deep coal roadway is a technical problem to be solved,85% of which occurs in the roadway,and its frequency and intensity increase dramatically with the increase of mining depth. This paper analysis the instability mechanism of deep coal roadway roof based on the elastic-plastic mechanics and fracture principle,ex-pounds the rupture instability mechanism of roadway roof strata with increasing stress and energy,derives the load,de-formation and energy conditions of rock burst,and elaborates the fission instability evolution law of composite roof which turns roof into the vicious circle of “interlayer separation-rock beam cracking-dynamic crack by dynamic load” or even instant caving. The instability process of deep coal roadway roof is closely related to the cooperatively extension of six main cracks under the superposition action of high stress and dynamic pressure. The six cracks of “one horizon-tal and five vertical” extend together and form a “door”-like breaking block to push into roadway and cause damage. The paper presents the six manifestation pattern of rock burst and dynamic instability,puts forward the effective unit control timbering countermeasure of “roof truss cable+roadway center long cable+roadway drift angle bolt”.