Abstract: In order to improve the biomass energy utilization efficiency and synthetic gas quality, based on AspenPlus simulation ,the characteristics of biomass gasification were studied by exergy method while pine, cornstalk and sawdust were selected as gasification feedstock. When the air/biomass mass flow ratio changed from 0.7 to 2.3 as well as the feedstock contained 30% moisture content, the exergy efficiencies of gasification process and the low heating values of synthetic gas were calculated. The biomass gasification processes were optimized through the methods of increasing gasifying agent temperature and drying biomass feedstock,. It shows that gasification performance can be greatly influenced by biomass species and its moisture content; The exergy efficiencies of gasification process and the low heat values of synthetic gas can be improved through reducing biomass moisture content and increasing gasifying agent temperature.