Recently, the energy supply uses mostly fossil fuels such as coal, petroleum, natural gas etc... however, they are limited and they present an issue for the environment. Biomass derived energy is considered promising for reducing the emissions of CO2, the significant contributor to global warming. Also it can be converted to various forms of energy through thermochemical conversion processes. In this study, a screw gasifier has been engineered for wood biomass gasification. Waste wood chip was used as biomass and the producer gas, tar; char were then achieved by gasification in the presence of CO2. The results showed that with the increase of the gasification temperature, the producer gas increased and the tar decreased. Also, due to thermal cracking, the light tar increased by the decomposition of the gravimetric tar. And a development of char pore structure was confirmed by SEM. The gasification of biomass in the presence of CO2 at 800oC produced an increase in the concentration of carbon monoxide according to the Boudoudard reaction and an increase in the char pore surface as well as its adsorption capacity. Thus the biomass gasification in the presence of CO2 was confirmed to be effective for the production of CO and the development of char.