Abstract: In order to study the mechanism of material instable rock burst in roadway, the elastic-plastic transformation characteristics of surrounding rock were analyzed by stress field theory, coal failure experiment and finite element simulation, the judgment condition of roadway coal wall rock burst was obtained based on the double yield contour model.The results show that the contour distribution of yield contour line appears hyperbolic according to the Mohr-coulomb yield criterion; when vertical stress is uniform, the value of yield contour line decreases with the depth of surrounding rock gradually, and it indicates that surrounding rock will break from the shallower to the deeper; when vertical stress increases gradually from the shallower to the deeper, the value of yield contour line contours increases with the depth of surrounding rock, it indicates that the roadway surrounding rock will break first in the deep, while the shallow surrounding rock will remain intact, the roadway is prone to rock burst in this case.Indoor uniaxial compression experiment and numerical simulation verify the theoretical analysis results.It is proved that the critical state of rock burst can be presented by the model of yield contour line judgment.