Abstract: In order to discuss the structure and gasification technique of the underground coal gasifier under different seam conditions, based on the model experi ment and site experiment, the structure and the technical parameters of the shaft type and no shaft type gasifier were studied and the well type long channel, large cros s section, two stage gasification technique and the no well type permeable gasification method were formed. The experiment results showed that the heat value of the C oal gas with air gasification would be over 4.18 MJNm3.When the enriched-oxygen gasification with an enriched-oxygen content increased from 30% to 80%, the effecti ve component (H2+CO+CH4) contents would be increased from 30% to 60%.The second stage of the two stage gasification could produce the gas with H2 component about 40% and the heat value over 11.45 MJ/Nm3.The channel connection parameters of the no shaft type permeable gasification would be when the air supply pressur e was 0.75 MPa and air supply value was 600 Nm3/h, the connection velocity would be 0.34 m/d and the channel equivalent diameter would be 0.39 m.The forward air supply gasification and the reverse air supply gasification would produce the same quantity of the coal gas.