Abstract: Fuel ethanol becomes one of the most important liquid fuel as the substitute of fossil fuel. Cassava fuel ethanol production is concerned, because cassava is not food materials. In this paper a life cycle energy assessment model of cassava-based fuel ethanol was established; Energy consumption of the three parts in the processes were calculated. Different technologies were discussed in the stages of ethanol conversion and their energy consumptions were analyzed to find out the best technical route for the producers based on the statistics. The results show that adopting new technologies, enhancing development of byproduct and employing livestock manures instead of chemical fertilizers can greatly improve the energy efficiency of the system.