The commercial twin-roll cast AZ31 magnesium alloy sheet is used in this paper. Multi-pass asymmetry rolling (ASR) is conducted on the sheet by small diameter rollers ASR at temperatures of 150℃, 200℃, 300℃, respectively, and the effect of ASR on the microstructure, texture, mechanical properties of rolled magnesium alloy sheet is investigated. The experimental results indicate that the mechanism of grain refinement is totally different at various temperatures: the grains are segmented into sub-grains by twins at 150℃, meanwhile, the dynamic recrystallization (DRX) is main grain refinement mechanism at 200℃ and 250℃, respectively. The texture evolution of the symmetry rolling (SR) and ASR sheet are analyzed, which predicts that the texture intensity of ASR sheet increases with rolling temperature elevated, but they are obviously lower than texture intensity of SR sheet.