Abstract: The pyrolysis of K₂CO₃-impregnated hemicelluloses, cellulose, lignin and pine was investigated by TG-FTIR to assess the influence of potassium on the pyrolysis mechanisms of the main components of biomass. The results show that the pyrolysis temperature range of hemicelluloses, cellulose and lignin is 200~350 ℃, 300~365 ℃,200~600 ℃, respectively. CO and CO₂ are mainly produced during hemicellulose pyrolysis, and levoglucosan and carbonyl group are mainly produced during cellulose pyrolysis, while solid product is the main product for lignin pyrolysis. The pyrolysis of the mixture of three components reveals that there are interactions among biomass components. Potassium could catalyze the pyrolysis process of hemicelluloses and cellulose, lower the pyrolysis temperature, and increase the char yields. Potassium influences the pyrolysis of cellulose most obviously, leading to a marked increase in the yields of CO, CO₂ and solid product, and a decrease in carbonyl compound yield. However, potassium has little effect on the char yield of lignin, and the catalysis of potassium for the pyrolysis of mixture weakens.