Hyperbranched polymer has low viscosity, high functionality, no chain entanglement and good solubility characteristics, provides a new way for epoxy toughening. Modifying the hydroxyl-terminated hyperbranched polyester (AHBP) obtained hyperbranched polyester with carboxyl end group (CHBP), not only has the toughening effect, but also play the role of a curing agent. Using CHBP as flexibilizer and curing agent, study its toughing effect on epoxy/MTHPA (EP/MeTHPA) curing system; CHBP molecular terminal all with carboxyl has the best toughening effect, impact strength achieves 18.5 kJ/m2; when the carboxyl terminal content reaches 40%, the impact strength of the epoxy resin is only 7.8 kJ/m, CHBP has no toughening effect at this time. When CHBP mass fraction is 15%, tensile strength achieves the maximum , 64.86 Mpa; when CHBP mass fraction is 15%, the Tg of the resulting cured epoxy resin is 106 ℃, increased about 6 ℃. Weihai CY Dendrimer Technology Co. Ltd forwards from “Study on carboxyl – terminated hyperbranched polyester modif ied epoxy resin curing systems” Wang Xiaoke, Tian Mi (Chongqing University of Science and Technology, Chongqing 401331) Thermosetting Resin, 2008,3 (23) , 25-28