one new kind of hyperbranched dispersant (HPBD) was prepared by grafting stearic acid and amino-terminated hyperbranched polymer (HBP-NH2), which was synthesized from methylacrylate and diethylene triamine by polycondensation.And then HPBD was used to modify the lignin/polypropylene composites.Experimental results revealed that the impact strength and bending strength of lignin/PP composites modified with HPBD are 40 and 34.7 percent higher than that of untreated systems, respectivrly.Meanwhile the thermal stability of modified systems as well as crystallization rate and degree of crystallinity of PP were increased.The Interface compatibility between lignin and PP was improved after treatment with HPBD.