Abstract: The microstructure and mechanical properties of general cast-rolled and compound energy field (electromagnetic field and ultrasonic wave) cast-rolled AZ31B magnesium strips after rolling with different rolling temperatures, passes and deformation ratios were studied. The results show that the compound energy field cast rolled magnesium strip was more likely to recrystallization than the general cast rolled magnesium strip under the same rolling conditions, and the grains size of the former was finer and more uniform than that of the latter. The precipitates of the former dispersed at grain boundaries in the mode of small particles and that of the latter dispersed at grain boundaries and near the grain boundaries. When the rolling temperature was 250, 300 ℃, the tensile strength, yield strength and elongation of the former after rolling for 3 passes increased by 11%, 22.2%, 145% and 13.6%, 19.7%, 127.8% than that of the latter after rolling for 3 passes, respectively.