Abstract: In order to provide basis data for entrained bed gasification experiment,taking the sub-bituminous coal as an object,the pressurized drop-tube furnace w as used to study the gas characteristics after coal pyrolysis under the different temperatures,pressure and different atmosphere.The effects of different pyrolysis conditi ons on char's structure,basic physical and chemical properties and CO_ 2 gasification reactivity were also studied.The results showed that hydrogen atmosphere obviou sly improve the yield of pyrolysis gas of CH_ _4,C_ _2H_ _4,and the yeild was over 3 times in nitrogen atmosphere,but had lttle effect on char residual volatile.The effect of r eaction atmosphere on weight loss rate varied with temperature,under the temperature of 600~800。C,constant pressure and hydrogen atmosphere, the weight loss was smaller compared to inert atmosphere,under the pressure of 0.5 MPa and hydrogen atmosphere condition,coal pyrolysis had greater weight loss rate than inert atmosph ere.As for gasification reactivity,gasification activity of the pyrolysis char prepared under the hydrogen atmosphere and constant pressure conditon,were higher than tha t of the nitrogen atmosphere pyrolysis char,but for the pressurized conditions,the effect of hydrogen on the gasification activity was not significant. The reaction with coal and hydrogen was mainly methanization,the pressurize could increase surface and pore volume of the char,but changed lttle on the chemical structure of coal char.