Abstract:  The pyrolysis characteristics and kinetics of fir sawdust were investigated via thermo gravimetric analysis at different heating rates. The distributed activation energy model (DAEM) was used to study the pyrolysis kinetics. The influence of temperature on organic structure of semi-char was analyzed by FT-IR. The pyrolysis of the samples was divided into four stages: extraction of water, transition, main pyrolysis and charring. As a function of conversion rate, the pyrolysis activation energies are between 103kJ/mol and 179kJ/mol. When the temperature is below 200℃, the function groups remain unchanged but a weaker intensity. With the increase of final temperature, the contained organic function groups in semi-char decrease greatly. When the temperature is above 500℃, the types of function groups remain unchanged and the main pyrolysis reaction process is completed.