The free-radical polymerization of N-acetyl α -aminoacrylic acid and the thermal properties of poly(N -acetyl α-aminoacrylic acid ) were investigated. From the results of kinetic investigation of N-acetyl α-aminoacrylic acid in DMF at 60℃, a rate equation of R_P=K_P [M]^0.97 [I]^0.59 was obtained. The overall activation energy for the polymerization was found to be 25.2 kcal/mol. The number-average molecular weight of poly(N-acetyl α-aminoacrylic acid) in DMSO at 85±0.1℃ was 3600. The DTA and TGA thermograms showed an endothermic peak for the first degradation of poly(N-acetyl α-aminoacrylic acid) at about 170℃ and weight loss(35.0%) by decarboxylation at about 200℃.