The continuous castings of wrought magnesium alloy AZ31 with or without the effects of electromagnetic field and Ca microalloying were investigated，and the appearances, microstructures and mechanical properties were compared. The results show that the ingots with the electromagnetic field casting (EMC) and Ca microalloying have smooth surface, and the defects, such as segregation, trapped oxide can be eliminated on the ingot surface. Through EMC and Ca microalloying, the microstructure is improved and the grain in the border and center of the ingot has a same size, the β-Mg17Al12 phases with the shape of dot and approximate dot distribute in the basal body uniformly. The yield strength and elongation increase by 15% and 90%, respectively, for the ingot with EMC and Ca microalloying compared to the ingot without EMC and Ca microalloying