The foreboding information and quantitative description of coal and gas outburst precursors are the basis and precondition for hazard prediction. In order to research the occurrence mechanism and look for the precursors of coal and gas outburst，a laboratory investigation using microseismic system was carried out. A large-scale trials about coal and gas outburst had been set up，and the procedure was monitored by the high sensitivity microseismic system. The shaking triggering by coal instability and rupture process could be acquired by microseismic system，and the results shows that shaking signals distribution has obvious zoning characteristics in the whole process，including incubation period，emergence period and evolution period. For this purpose，the corresponding methods of hazard precursor quantitative description on the microseismic index were established. The indexes included N(number of events)，R(event rate)，E(energy) and BR(big event rate). The laboratory analysis and field measurement results show that the outburst process has obvious zoning features，and different stages have different signal features. It can be provided for the hazard prediction in advance，and be validated the occurrence mechanism further.