Abstract: This paper is to focus on the transport of coal bed gas within the micro-structure of coal-rock mass，where gas pressure and its flow were analyzed.The results indicate that the movement of gas within micro-crack of coal-rock would be able to result in gas pressure wave，namely shock and expansion wave，whose propagation and cumulative process is attributable to the gas outburst of coal-rock.The changes of gas pressure wave certainly control the gas movement containing gas pressure and flow，which in turn accelerates the propagation and coalescent of crack of coal and then causes the chain interaction of two-phase flow.It is therefore postulated that outburst of coal-gas possibly follows the hypothesis of fluids dynamics.

Key words: Coal and gas, Outburst, Fluids dynamics, Gas pressure wave