Abstract: Aiming at evaluating the environmental contribution of mixed alcohol production technology from biomass as agricultural and forestry residues,hybrid life cycle assessment（LCA）was applied to assess the properties of fossil fuel consumption and greenhouse gas（GHG）emission of a 100 t/a-scale system via gasification and catalytic conversion pathways.The effect of four types of feedstock-based alcohol system,including cotton straw,maize straw,wood chips and tree pruning,was analyzed,according to the simulation results from mixed alcohol production model and the life cycle inventory.The life cycle studied included the stages of agricultural/forestry planting,collection/storage/transportation,production and alcohol transportation.The results shows that the potentials of fossil fuel consumption and GHG emission of the 100 t/a-scale system are in the ranges of 589～734 k J/MJ alcoholand 63.2～80.8 g CO₂ eq/MJ alcohols respectively.The main contribution of the environmental potentials derive from the electricity input from grid and the production equipment/plant constructions in mixed alcohol production stage,which account for more than 80% of total ruglues.Of the four tipical of feedstocks,maize straw-based mixed alcohol system shows the highest environmental impact,which may be related to the low carbon content of maize straw and low alcohol yield.As the production capacity of maize straw-based alcohol system is expanded to 50,000 t/a,the potentials of fossil fuel consumption and GHG emission are decreased to 192 kJ/MJ alcohols and 16.6 g CO₂ eq/MJ alcohols respectively as a combined cycle is applied to recovery heat for electricity generation and the system is self-sufficient of electricity.