Pyrolysis kinetic characteristics of sawdust samples were studied at heating rates of 30, 40, and 50 degrees C center dot min1 by thermogravimetric analysis. The pyrolysis of sawdust could be divided into five stages, and Sestak's complex mechanism was used to study the mechanism of each stage. The thermal degradation mechanism, activation energy, and frequency factor of each stage were obtained by multi-linear regression using Microsoft Excel. The results showed that the Sestak-Berggren function is very suitable for the mechanism analysis of complex systems.