Abstract: Fast pyrolysis of the industrial lignin made by acid precipitation method was investigated at 400℃～700℃，and the liquid pyrolysate obtained was analyzed by Chromatography/Mass Spectrometry (GCMS) to investigate the influence of pyrolysis temperature on the composition of liquid pyrolysate product. The results show that the lignin pyrolysate is composed of singlering phenolic compounds, including phenol(phydroxyphenyl type) as the main component, guaiacol(guaiacyltype) and 2,6dimethoxyphenol(syringyltype), and their methlylic or ethylic derivatives. In the temperature range of 400℃~600℃， the variety of the distribution pattern and the yields of the compounds of pyrolysate is minor. However, the proportion of methoxyphenolic compounds decreases significantly and the proportion of phenol increases markdly when the temperature is up to 600℃~700℃. At 700℃, the relative content of phenol reaches to about 27.81% two and half times higher than that at 400℃. In addition, the formation of aromatic hydrocarbons is enhanced, and small amounts of indene, naphthalene and their derivatives are produced as well.