Abstract: An experiment was carried out in lab on vertical twin-roll casting machine with magnesium alloy AZ31 ingots as workpiece which were cold rolled to form strip then annealed directly. The parameters in the processes of vertical twin-roll cast-rolling and annealing, and the microstructure evolution of the finished cold strip were investigated. The results showed that the magnesium alloy strip is obtained successfully due to reasonable process parameters, especially in the twin-roll cast-rolling process both the quick chilling and pressured solidification improve the solidified structure of the strip of which the maximum deformation can be up to 40.7% if the magnesium alloy billet is cold-rolled directly. For the cold-rolled Mg alloy plate after annealing at 350°C for 30-60 min, the equiaxed fine grain structure with average grain size 9-10μm is available.