It is of great significance to predict the grain evolution of magnesium alloy pipe in the process of pilger rolling deformation in real time for controling the final performance of the magnesium alloy pipe. In this paper, the cellular automata model based on dynamic recrystallization, static recrystallization, static recovery, grain coarsening and grain topological deformation was established by rolling experiments on AZ31 magnesium alloy pipes on a Pilger mill.Finally, the results of each pass obtained by the finite element calculation are combined with the cellular automata to obtain the grain evolution of the magnesium alloy pipe in the rolling process in real time. It is found that the grains are continuously generated during the rolling process. and was finally verified by experiments.