A die-casting method and a device for use in the die-casting method are disclosed. The casting material, which can be liquid metal, semi-solid metal or metal-matrix composite, in the shot chamber of a die-casting machine is driven to flow with high shear rate to mix homogeneously by the electromotive force induced with at least one low-frequency shifting electromagnetic field. The temperature and the microstructure of the casting material near the shot chamber are further controlled and perturbed by at least one high-frequency electromagnetic field to minimize the temperature difference or the growth of dendritic microstructure. To ensure the efficiency of the electromagnetic fields, the shot chamber is made of non-magnetic material and its wall thickness is less than three times the penetration depth of the electromagnetic fields. The shot chamber is surrounded by at least one solenoid coil, a conducting shield and at least one electric motor stator. The conducting shield, which only allows the low-frequency electromagnetic field to penetrate, protects the stator from being overheated by the high-frequency electromagnetic field.