A series of hyperbranched polyester-amides (S1, S2, S3) with trimethylolpropane as a core molecule were synthesized using core-dilution/slow monomer addition strategy. The products were characterized by FTIR, C-13 NMR, GPC, TGA, hydroxyl value measurement, and viscosity measurement. The result showed that the hyperbranched polyester-amides synthesized had narrow molecular weight distribution and high degree of branching (DB). The hyperbranched polyesteramides synthesized were used as crosslinkers for polyurethane curing systems and the mechanical properties of the polyurethane curing systems were investigated. It was found that the best tensile property and tear strength were obtained when the S2 were used as crosslinkers and the molar ratio of -OH and -NCO was 1 : 1. It was also found that the polyurethane curing systems had the highest hardness and T-g when the S3 were used as crosslinkers. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 957-963, 2011