Abstract: Based on distribution characteristics of rock burst, combining with occurrence conditions of 11-2 coal seam in Zhuji Mine, the occurring process of rock burst is analyzed under the conditions of two gas pressures in paper. Mobile mechanism of coal is studied when rock bust occurs, and evolution pattern of coal fracture, gas flow state pattern and stress distribution curve are obtained. The results showed that coal fracture process is almost same under different gas pressures; soft coal fracture is relatively acute in initial stages under high gas pressure, i.e. higher gas flow, greater coal fracture depth, very serious rock burst; the slip can be regarded as rolling friction between coal seam and roof.