In AZ31 (Mg–3Al–1wt% Zn) magnesium alloy sheets rolled by differential speed rolling (DSR) at 423 K, many twins appeared at a low reduction rate of 25%, and fine grains (∼1 μm) having approximately the same size dominate at a high reduction rate of 55%. In addition to these microstructural changes, the rolled sheets showed a strong texture characterized by (0 0 0 2) pole tilting about 7 degree from the normal direction (ND) towards the rolling direction (RD) throughout the whole thickness of the DSR sheets. The ( 1   0   1 ¯   1 ) pole figure as well as TEM images of the specimen prepared at a reduction rate of 55% indicated that the activation of a prismatic slip played an important role in bringing about dynamical re-crystallization.