Abstract: Alkylation of wheat straw alkaline lignin was conducted by reacting lignin with different alkyl halides.Solubility and surface activity of lignin were improved after alkylation. Effect of alkylating reagents,reaction time, temperature and pH value on alkylation was investigated in detail. Surface activity of alkaline lignin was improved by alkylation with dodecyl bromide at 170 ℃,3 h.Further improvement in surface activity was achieved by sulfonation of the alkylated soda lignin at 130 ℃,pH 14.