Abstract: The behavior of several antioxidant in poly(methyl methacrylate)(PMMA) was studied using thermo gravimetric analyzer（TG）and the kinetics of thermal degradation was analyzed with Kissinger, Flynn-Wall-Ozawa, and Flynn methods. It showed that four kinds of antioxidant, 1010, 1076, 702, and BHT increased the initial thermal degradation temperature by 70 °C at a content of 0.5 wt ‰. Further increasing the loading the change was moderate. The kinetics analysis showed that the antioxidant could only improve the thermal oxidative stability at the initial period of degradation（the weight loss less than 30 %）, after which the stabilizing effect of antioxidant on PMMA were reduced due to the antioxidant escaped from the system at a higher temperature than the melting point of antioxidant.

Key words: poly(methyl methacrylate), antioxidant, thermal oxidative stability, kinetics