Abstract: The oxy-fuel combustion of biomass technology combines the advantages of oxy-fuel combustion and biomass combustion,which can not only reduce the consumption of fossil fuels,but also easily achieve CO_2 capture. The most significant feature of oxy-fuel combustion is that the oxygen concentration in the atmosphere is more than 21%,which has a significant effect on the ignition behavior of biomass. Cellulose,hemicellulose,and lignin are the three main components of biomass. Therefore,studying the ignition and combustion behavior of these three components under oxy-fuel conditions is the basis for the study of biomass ignition and combustion. In this work,a drop tube furnace combined with a high-speed camera were utilized to study the ignition behaviors of cellulose,hemicellulose,and lignin particles of 74-154 μm at the temperature of 1 273 K under O_2/CO_2 atmosphere with oxygen concentration of 21%,30%,50%,70%,and100%. The radiant energy analysis technology was used to calculate the temperature of particles in the ignition picture. The results show that cellulose and hemicellulose change from hetero-homogeneous ignition to homogeneous ignition and lignin changes from homogeneous ignition to heterogeneous ignition with the increase of O_2 concentration. The ignition mechanisms of cellulose,hemicellulose,and lignin change at 30%,70%,and 50% oxygen concentration,respectively. The ignition of cellulose is sensitive to the change of O_2 concentration. When the _2 concentration exceeds 30%,the cellulose char ignites firstly. The heating rates of hemicellulose and lignin increase with the increase of O_2 concentration. For hemicellulose,it can be attributed to that the burning proportion of hemicellulose volatiles decreases and the burning proportion of hemicellulose char increases with the increase of O_2 concentration during the combustion process. For lignin,it is because the combustion of lignin char is enhanced with the increase of oxygen volume fraction. Moreover,the combustion time of hemicellulose and lignin decreases with the increase of O_2 concentration,both of which are due to the enhancement of their char combustion with the increase of oxygen content. Furthermore,the lignin char will melt and expand under higher oxygen concentration,forming an obvious expanding flame.