The mechanical properties of the AZ31B alloy sheets processed by differential speed rolling (DSR) from the cast ingots homogenized at two different conditions were investigated. There still existed the uneven distribution of Al and Zn in the ingot homogenized at 673 K for 6 h, while it was homogeneous for the ingot homogenized at 723 K for 24 h. Compare with the sheet rolled from the ingot homogenized at 673 K for 6 h, the sheet rolled from the ingot homogenized at 723 K for 24 h exhibited a lower proof stress, a larger elongation, and a lager strain hardening exponent. The improvement in the ductility can be attributed to the elimination of the microsegregation of Al and Zn in the matrix.