The temperature distribution of the AZ31 magnesium alloy in the rolling deformation zone was analyzed by numerical simulation. The empirical formula of the average temperature of the magnesium plate after rolling with respect to the roll temperature, the rolling velocities, the rolling reduction rate, and the thickness of the plate was established and supplemented with corresponding experiments. verification. The results show that when the magnesium plate is thin and the rolling velocity is small, the plastic deformation heat of the center layer of the magnesium plate is transferred to the surface in the rolling deformation zone. The temperature rise of the center layer cannot represent the temperature rise caused by the deformation of the magnesium plate. The average temperature of the magnesium plate after rolling is positively related to the roll temperature, rolling velocity and rolling reduction rate, and inversely related to the sheet thickness. The maximum relative error between the calculated and experimental values of the formula is 8.34%, and the average relative error is 7.4%. The formula can well predict the average temperature of the magnesium plate after rolling. The proposed empirical formula for magnesium plate temperature prediction is conducive to the realization of "isothermal rolling" control of AZ31 magnesium alloy sheet; it is of guiding significance for the reasonable formulation of magnesium alloy rolling process system and the selection of subsequent rolling equipment