Abstract: The research progress on removing solidification forming defects of steels by introducing external energy fields (electromagnetic field and ultrasonic field) is reviewed. It is with the aid of stirring of electromagnetic force to refine grain, reduce porosity, segregation and cracks, while the application of electromagnetic field on liquid steels during solidification. It is with the aid of cavitation effect and acoustic streaming effect of ultrasound to refine grain, reduce inclusion, so as to enhance mechanical property of steels, while the application of ultrasonic field on liquid steels during solidification. The electromagnetic-ultrasonic compound fields will be a new method to remove solidification forming defects of large size continuos casting steels billet, and some problems need to consider for the new method in follow-up research are presented.