Abstract:Isoion spectrum，Fourier Transform Infrared Spectroscopy and Electron spin resonance spectrum were used to analyze chemical properties of the wood in different year-ring parts in this experiment．The results showed that there was a greater variation in chemical characteristics between wetheartwood and normal sapwood．Compared with sapwood， wetheartwood contained much higher ash and the inorganic elements such as K，Ca，Na， etc．It is evident that there were polyphenols acids，esters and free radicals which affected the colour and the water content in the heartwood．Moreover，it appeared that the characteristic of wetheartwood depanded mainly on the genotype of the clones．