In view of the factors influencing the outburst of coal and gas, such as crustal stress, gas, physico-mechanical properties of coal rock, and geological structures, it is proposed that the processes of coal and gas outburst consist of three stages including formation and development of outburst source. Based on a typical outburst accident occurred in Nantong mine, the conditions for excitation and occurrence of coal and gas outburst are investigated by deductive method. The results indicate that the rock fr...