The copolymer of methacrylic acid anhydride and N-2-pyridyl bi(methacryl)imide was prepared based on the reaction of polymethacrylic acid with 2-pyridylamine. The molecular structure was characterized by H-1-NMR, FTIR, UV-Vis, and circular dichroism techniques. The physical properties of polymethacrylic acid change significantly after an introduction of 6 mol N-2-pyridyl bi(methacryl)imide unit. In particular, the thermal degradation of the polymer was systematically studied in flowing nitrogen and air from room temperature to 800degreesC by thermogravimetrv at a constant heating rate of 10degreesC/min. In both atmospheres, a four-stage degradation process of the copolymer of methacrylic acid anhydride and N-2-pyridyl bi(methacryl)imide was revealed. The initial thermal degradation temperature T-d, and the first, second, and third temperatures at the maximum weight-loss rate T-dm1, T-dm2, and T-dm3, all decrease with decreasing sample size or changing testing atmosphere from nitrogen to air, but the fourth temperature at the maximum weight-loss rate increases. The maximum weight-loss rate, char yield at elevated temperature, four-stage decomposition process, and three kinetic parameters of the thermal degradation were discussed in detail. It is suggested that the copolymer of methacrylic acid anhydride and N-2-pyridyl bi(methacryl)imide exhibits low thermal stability and multistage degradation characteristics.