Abstract: Several kinds of catalysts of sulfuric acid-ionic liquid were first used in the synthesis of polymerized rosin. Sulfuric acid-1-n-butyl-3-methylimidazolium tetrafluorobate and sulfuric acid-1-n-octyl-3-methylimidazolium tetrafluorobate have high catalytic activities. For H2SO4-(C8 mim)BF4, effects of the kinds of solvents, amount of H2SO4, reaction temperature and reaction time were studied. The optimum reaction condition was as followed: m(rosin) and m(toluene)=1:1,catalyst dosage 30% (based on rosin mass), reaction temperature 70℃, reaction time 4 h, sofening point of the polymerized rosin could reach 135℃, and acid value could be 142 mg/g. The regeneration of H2SO4-(C8 mim)BF4 was investigated. The results showed that H2SO4-(C8 mim)BF4 could be excellently reused. By using this catalyst, some defects of traditional catalysts were overcome, and the product could be conveniently separated by decantation.