Fast pyrolysis of cellulose, xylan, and lignin was experimentally conducted between 350 and 650 degrees C in a tube furnace, and the effect of temperature on pyrolysis products (char, noncondensable gas, and bio-oil) was investigated. The yields of char, noncondensable gas, and bio-oil were quantified using gas chromatography and gas chromatography with mass spectrometry. The noncondensable gas mainly consists of CO, CO2, CH4, and H-2. The bio-oil includes acids, ketones, aldehydes, esters, benzenes, alcohols, alkenes, phenols, alkanels, carbohydrates, etc. The results show that cellulose is the principal source of carbohydrates and phenols are the basis of the bio-oil from lignin, while the bio-oil from xylan mainly consists of acids, ketones, aldehydes, and phenols. The char yields for the three components decrease with an increase in temperature, and the gas yields and bio-oil yields increase with an increase in temperature, reach a maximum at a certain temperature, and then decrease after that temperature. The maximum bio-oil yields for cellulose, xylan, and lignin are 65, 53, and 40%, respectively; and their corresponding temperatures are 400, 450, and 500 degrees C, respectively. To investigate a relationship between biomass and three major components (hemicellulose, cellulose, and lignin), the pyrolysis of three typical biomass samples (rice straw, corn stalk, and peanut vine) was also studied, and the additivity law is adopted to predict the product components of biomass pyrolysis based on the content of hemicelluloses, cellulose, and lignin. The results show that the additivity law can predict reasonably the trend of product yields of biomass samples from their composition of hemicelluloses, cellulose, and lignin.