Abstract: On the basis of analyzing nozzle clogging, the effects of feeding speed, the amount of Ca-Fe cored wire during Ca-treatment and nozzle diameter on the castablity of billet continuous casting for low-carbon low-silicon Al-killed steel were studied by an orthogonal test in line with the on-site condition of No.3 Steelmaking Shop of Ma-Steel, China. The results showed that increasing the feeding speed, the amount of Ca-Fe cored wire and the diameter of the tundish nozzle can prevent blockage. After adopting these parameters proposed, 8-10 heats could be cast in sequence, and the surface quality and internal quality of the billets are satisfactory.