Abstract: In order to accurately evaluate the risk of rock burst in mine, based on the analysis of the evolution laws of physical and mechanical parameters of roof, coal seam and floor plate, the mechanical model of combined coal and rock mass is set up, and the critical conditions for the stability and failure of the combination are determined. The criteria for evaluating the impact tendency is established, when V_T is less than 10, there is no impact tendency; when V_T is less than 20 and greater than or equal to 10, there is weak impact tendency; when V_T is greater than or equal to 20, there is strong impact tendency. The test results show that the energy release speed index of the combined coal rock mass is simple and the result is unique, and it can well evaluate the impact risk of coal mass.