Abstract: The lignin was recovered from the alkaline paper-making black liquor by acidulation precipitation.The modified sodium lignosulfonate was prepared by using Na_2SO_3 through hydromethylation and polycondensation.The recovery of lignin and reaction condifions for treatment of modification of sodium lignosulfonate were inrestigated.The results show that the modified sodium lignosulfonate prepared has good properties of scale-resistance.