Abstract: The uniaxial compression behavior of amorphous polymethylmethacrylate (PMMA) was studied between 110 ℃ and 130 ℃. It showed that PMMA was sensitive to the temperature, its yield stress decreased with increasing temperature. When the temperature was higher than 120 ℃,the yield peak disappears, showing good plasticity. PMMA was also sensitive to the strainrate. The strain hardening was gentle when the rate was ranging from 0.1 s-1 to 0.001 s-1. The microscopic mechanism above temperature and stressstrain dependent behavior was explained.