Abstract: The gasification of pine sawdust in an updraft gasifier was carried out at 400~900℃ to investigate the effect of temperature on the composition of the liquid products and their chemical origins. The liquid products were analyzed by using Fourier transform infrared spectroscopy (FT-IR) and gas chromatography/mass spectrometry (GC/MS). The results showed that the primary liquid products are mainly composed of oxygenated compounds such as ketones, furans and guaiacols. The composition of the liquid products change largely with the gasification temperature: the guaiacols are transformed to phenolics at 400~500℃; the ketones and the furans are converted to phenolics at 500~600℃; the transformation of the phenolics to indenes and PAHs (polycyclic aromatic hydrocarbons) occurs at 600~700℃ and the phenolics to PAHs at 700~900℃; at 900℃, the liquid products were exclusively composed of larger PAHs.