Abstract: Water pre-injection control measure in coal seam is widely adopted at rock burst working faces, which causes the increase of water content in coal seam, and directly affects the amount of drilling cuttings weight in the decision process of rock burst hazard. Taking the 21141 working face in Qianqiu Coal Mine as an example, the method of using drilling bits way to monitor rock burst hazard and divide grade is described. Based on the test data of water absorption and content of coal sample, normal quantity of dust coal at water pre-injection area is optimized. The optimization results are applied to the actual monitoring, which shows good results.