Abstract: Using benzene and toluene as model compounds of biomass tar, the effect of temperature, steam content and space velocity on catalytic conversion were investigated in a fixed bed reactor over dolomite and cordierite catalyst. The results indicate that the conversion rate is improved with increasing temperature and decreasing space velocity. At 900℃, the conversion of toluene over cordierite and dolomite catalyst could reach 95%, using a molar ratio of steam/carbon (S/C mol ratio) equal to 1.5. At the same reaction temperature, the conversion of benzene over cordierite and dolomite catalyst could reach 61% and 53% separately, using a molar ratio of S/C mol ratio equal to 1.0. High steam content is favorable to adjust gas component. Stability experiment indicates that coke deposition is the key reason for catalyst deactivation.