Abstract: Thermogravimetric analysis (TGA) was used to investigate the combustion characteristics and kinetics of cellulose, xylan and lignin. The influences of different heating rates (20, 40, 60, 80℃/min) on their combustion behavior were analyzed. The combustion characteristic parameters and the kinetic parameters were determined. The results show that: The weight loss of cellulose and lignin combustion is concentrated in the burning process of the volatile matter and coke respectively, but that of xylan combustion is large in these two processes. It is observed that the optimum reaction order of cellulose and lignin is one in the low temperature region and two in the high temperature region, while that of xylan is one in two temperature regions.