Abstract: The effects of the bottom shapes (well-bottom, flat-bottom and mountain-bottom) of submerged entry nozzles (SENs) and the well depth of well-bottom SENs (0, 10 and 20 mm) on the level characteristics of high-speed continuous casting molds were investigated by full scale water modeling and plant trials. Fluid flows in the molds with well-bottom and flat-bottom SENs are more symmetrical than those with mountain-bottom SENs. The decreasing order of meniscus velocity in the molds is from mountain-bottom, flat-bottom to well-bottom SENs. Comparative studies on the level characteristics of the molds between well-bottom SENs with different well depths show that well-bottom SENs with the well depth of 10 mm can decrease the level fluctuation and meniscus velocity, and this is helpful to prevent slag entrapment. Plant trials indicate that level fluctuation in the molds with mountain-bottom SENs is higher than that with well-bottom SENs, and this agrees well with the water modeling results. The power density spectra of level fluctuation using mountain-bottom SENs are about 10 times as large as those using well-bottom SENs at the frequency ranging from 0. 003 to 0. 05 Hz.