Abstract: The effect of steam content and reaction temperature on the catalytic conversion of Naphthalene, which was chosen as the model compound in pyrolysis gas from biomass, has been investigated with a Ni-Pt/Al2O3 catalyst in a fixed bed reactor. It has been confirmed that increasing the reaction temperature not only enhances the conversion of naphthalene and H2-, CO-yield, but also improves the CO-selectivity, however the H2-selectivity and the carbon deposit decrease. High steam content is favorable to increase the naphthalene conversion, the H2-yield and -selectivity, but the CO-yield and -selectivity as well as the carbon deposit decrease with increasing steam content. It is also found that the concentration of benzene, a by-product of naphthalene conversion, increases with the enhanced steam content and reaches a maximum at 700 ℃.