Abstract:In this paper, the influencing factor of the blow hole defect in continuous casting slab and hot rolled plate was analyzed. The main reason of surface blow hole defect in continuous casting slab is that the argon gas insufflate the mold from the upper nozzle, argon sealing and submerged entry nozzle cannot float effectively. The argon blow hole was captured by solidified continuous casting slab shell and induced the surface blow hole defect in continuous casting slab. The blow hole mostly distributed to the wide-face shell edge near the narrow side position. The blow hole quantity in the center of wide-face and the 1/4 of wide-face shell is few. The surface blow hole defect in continuous casting slab and hot rolled plate can be eliminated by utilizing no argon blowing.