An innovative microwave irradiation device is developed to investigate effect of microwave irradiation on pore morphology of coal powder. This device with several distinguished highlights, such as real-time infrared temperature measurement, gas replacement, process parameters controls, and large size samples testing. Specifically, results of effect of temperature (25-300 degrees C) and microwave power (1-6 kW) on pore morphology was evaluated by the mercury intrusion porosimetry method. The pore connectivity decreases at first then increased with incremental processing temperature or microwave power. The percolation threshold increases with increased heating temperature or microwave power. The total pores volume increases with increased processing temperature or microwave power. The total specific surface area increases firstly then decreases with increased temperature or microwave power. These suggest that effect of microwave irradiation on pore morphology is obvious. Several possibilities for microwave energy application in the field were discussed, including drilling borehole from the ground to the payzone, drilling up-hole or down-hole from the roadway to the payzone, drilling borehole along the coalbed. The process economics were also discussed. It implies that as a new technology microwave energy may have the potential for the degassing coal seams.