Pyrolytic lignin was separated from bio-oil. The structure and pyrolysis characteristics of pyrolytic lignin were compared with an alkali lignin. The content of main elements in two kinds of lignin was the same level, but the content of carbon was higher and the content of oxygen was lower in pyrolytic lignin compared with alkali lignin. It was shown that alcoholic hydroxyl group in pyrolytic lignin was less than alkali lignin with Fourier transform infrared spectroscopy(FTIR) analysis. Thermogravimetric analysis (TGA) revealed that the rate of weight loss of pyrolytic lignin was quicker at low temperature and the thermal stability was worse compared with alkali lignin. It was observed that the composition of pyrolysis products of two kinds of lignin was largely different by the experiments of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The contents of aromatic compounds in pyrolysis products of pyrolytic lignin were both higher than alkali lignin at two temperatures. The main components in pyrolysis products of alkali lignin were alcohols, while the content of aromatic compounds was low at 250℃. However the content of aromatic compounds in pyrolysis products of alkali lignin increased at 550 ℃, the content of alcohols decreased, and large numbers of acetone were formed.