Lignin is a poylmer present in the structure of many polar groups, more particularly hydroxyl groups, lignin with strong intermolecular and intermolecular hydrogen bond energy, and therefore the original lignin insoluble in any solvent . Separation of lignin, because of reduced synthesis and degradation occurs, many physical properties change, the change in solubility resistance. Alkali lignin in acidic and neutral media, insoluble in water, but the composition Los having strong hydrogen bonding solvent such as an aqueous solution in NaoH (the pH value of 10.5 or more), dioxane, acetone, methyl cellosolve-based solvent, pyridine and the like; soluble in various lignin sulfonate aqueous solution PH value. Fu not in organic solvents. Wood is a type of cable was originally difficult biodegradable high molecular polyarylate, unit mass star low BOD value of lignin, such as black liquor from the soda lignin leather BOD is 0.10-0.11g / g lignin, but in some special strain effect, lignin derivatives can be raw materials of degradation and absorption, and thus removed from the straw; Further, wooden cable and hemicellulase degrading enzymes also have some options of lignin degradation.