Abstract: The law of the strain-rate-temperature equivalence of PMMA up to yielding is discussed based on the viscoelastic/plastic constitutive model and experimental data of stress-strain curves at the range of T = 233-343K and ε=1.0×10-4-1.0×10-1s-1. The existence of the shifting factor ar and normalized stress-strain master curve shows the existence of strain-rate-tem. perature correspondence of PMMA before yielding.