Abstract: Based on the seepage theory of gas flow in coal seams and elastic theory of coal deformation and combining them with the relationship equations between gas permeability and damage, a mathematical model of coupled solid-gas flow in coal and rock formations in the failure process of coal and rock was established. Using the gas pressure incorporated RFPA code, the mining induced instantaneous outbursts, gas pressure changes before and after outbursts, gas drainage and associated characteristics of gas permeability and gas pressure of coal seam during mining were numerically simulated. The results offer some theoretical indications to further investigate the mechanisms of instantaneous outbursts and gas drainage and give some precautions to prevent their occurrences in collieries.