Two dendrimers with pendant benzoxazines, named 1.0 G benzoxazine (1.0G BZ) and 2.0 G benzoxazine (2.0G BZ), were prepared by using 1.0 G PAMAM or 2.0G PAMAM, formaldehyde and phenol. The structures of 1.0G BZ and 2.0G BZ were characterized by H NMR, FT-IR, and the curing behavior was investigated by different scanning calorimetry (DSC). The thermal properties of the cured resin of 1.0G BZ and 2.0G BZ were also investigated with thermogravimetrical analysis (TGA).