In view of the process characteristics of thin slab casting with a vertical-arcmould and super thin submerged nozzles, the fluid flow laws in a mould and in scarch of reasonablesu bmerged nozzle patterns have been physieally simulated. The fluid flow states of several typiealnozzleS in moulds were studied through water model experimen ts. The shape and dimensions of asuitable submerged nozzle have heen optimized for industry trials.