The sulfonated alkali lignin (SAL) with different sulfonic group contents and the sulfonated alkali lignin polyethenoxy ether (SAL-PEG) with different crosslinking degrees and molecular weights were prepared.The effects of the sulfonic acid group content and the PEG nonionic long chain on the behaviors of SAL and SAL-PEG in solution were studied by dynamic light scattering (DLS).The results showed that the aggregation behavior existed in 1.0 g/L SAL aqueous solutions.And the degree of aggregation decreased with increasing the sulfonic acid group content of SAL

because the more sulfonic acid groups caused the increasing molecular stretch degree of SAL.The addition of 2 mol/L NaCl made the molecular configuration of SAL become compact in solution and the aggregates of SAL were disaggregated evidently.The SAL-PEG mainly took the form of single molecule in 1.0 g/L aqueous solution

with weak aggregation behavior

and the hydrodynamic radius (Rh) of SAL-PEG was proportional to its molecular weight and the crosslinking degree.The addition of 2 mol/L NaCl made the PEG nonionic long chain of SAL-PEG become compact severely in solution

and Rh of SAL-PEG was significantly reduced.Meanwhile the degree of reduction was proportional to its molecular weight and cross-linking degree

but the degree of aggregation of SAL-PEG was still weak.