Abstract: An Aspen Plus gasification model for dry birch chips in a downdraft fixed-bed gasifier was developed,in which the predicted the gas composition and gas calorific value and agreement well with the literature results. The sensitivity analysis module was used to simulate the effects of oxygen carbon ratio and CO₂/C on gasification results,and the staging gasification process of O₂/CO₂was proposed.Compared with the conventional CO₂gasification characteristics,the influence of CO₂/C on gasification results was analyzed. The results show that the gasification gas with high H₂and CO concentrations can be obtained with pure oxygen gasification,but its net CO₂emission is high,and the carbon conversion ratio gradually increases and the cold gas efficiency first increases and then decreases with the increase of oxygen to carbon ratio. When CO₂is used as gasification agent,the net CO₂emission decreases gradually with the increase of CO₂/C,but the carbon conversion and cold gas efficiency decrease greatly. Compared with conventional CO₂gasification,O₂/CO₂staged gasification can effectively increase carbon conversion and cold gas efficiency while maintaining low CO₂emission.