The life cycle assessment and inventory analysis of biomass to gasoline through MTG and STG methods were conducted to evaluate whether the process would be environmentally friendly. Energy consumption and pollute emission evaluation of the two entire life cycles were compared under the same boundary definition. Global warming potential of BIO-MTG and BIO-STG are both negative and close when the CO_2 absorbed during the biomass growth is considered. The other LCA potentials appear to be close for the similarity of process design. The energy consumption of BIO-MTG is higher than that of BIO-STG,and the gasoline yield of BIO-MTG is 14% higher than that of BIO-STG when the feedstock with same quality is given for the two methods. The unit energy consumption of BIO-MTG is less than that of BIO-MTG.