Thermochemical conversion from biomass to higher alcohols is a promising route for manufacture of higher alcohols in an environmentally sustainable way. In this study, a production system of biomass gasification and subsequent higher alcohol synthesis was designed and simulated. Two core modules of the processes (biomass gasification and alcohol synthesis) were constructed, and the optimum reaction conditions were discussed in. detail. The results showed that the lower ER (the equivalence ratio of oxygen/fuel) (ER = 0.2) could increase the CO content in the gasification product. By changing the mass ratio of steam to biomass (S/B), hydrogen-rich syngas could be obtained for higher alcohol synthesis. For the synthesis of higher alcohols from syngas, higher temperature was conducive to CO conversion but also can increase the content of byproduct such as CO2 and CH4. Higher pressure and H-2/CO (1.0-2.0) were both in favor of the production of higher alcohols. Then the process simulation was based on two cases, which were mainly divided by the difference in power supply sources. In case 1, part of the electricity demand was provided by an external power source while, in case 2, the process was devised to be completely self powered by adding in a gas and steam combined cycle power unit. An assessment of the material flow, energy consumption, energy efficiency, and exergy flow of the two cases was made according to the simulation results. The alcohol yield was 25.1 and 19.4 wt % for case 1 and case 2, respectively. And the energy efficiencies of the two cases were relatively close to each other (34.1% and 33.2%, respectively). About 33.5% exergy input was converted to alcohols in case 2, lower than case 1 (39.6%). The exergy loss in the power generation unit of case 2 was higher, resulting in a higher total exergy loss. For case 2 the electricity demand can be balanced by the system itself without any fossil fuel usage, which was quite attractive and promising from the aspect of environment protection and cost competitiveness.