Abstract: The characteristics of biomass gasification in a fluidized bed with porous media as bed material were investigated by experiments. The effects of gasification temperature (600℃~900℃), oxygen enrichment in gasifying agent (0.21~0.50), steam flux and type of porous bed materials on gas composition were analyzed. The results show that the content of combustible gas increases with increasing gasification temperature.  The hydrogen composition is improved from14.52% to 19.71%, but the CO composition is lowered from 43.41% to 36.41% by increasing the oxygen enrichment. There exists an optimum value for the steam flux during gasification. Different porous bed materials have different catalyses for the formation of H₂, CO and the cracking of hydrocarbons.