In this paper, pyrolysis chemical kinetics of wood base materials was investigated with thermogravimetric analysis. The results showed that:1.After the materials lost water, pyrolytic reaction of wood samples and α cellulose consisted of two stages but the reaction of Klason lignin was in only one stage.2.Activation energy for thermal degradation of the wood samples were in the order:α cellulose>wood samples>Klason lignin.3. Order of reaction of different stages of the wood samples and α cellulose were 1, but orders of reaction of Klason lignin were different with different wood species.