Abstract: A 1:10 water model for a 260 t converter has been established and the effect of bottom-blowing gas flow rate, the quantity and position of bottom nozzles on bath mixing time has been investigated. The typical feature of flow field in the bath has been observed under differentbottom blowing condition. The results show that mixing time of converter bath reduces with the increase of bottom blowing gas flow rate. When total flow rate is 12 L/min, mixing time is longest with twelve bottomblowing nozzles at 0.6R position. When eight nozzlesis used, the life of nozzles reaches 5000 heats,[%C]•[%O] is smaller than 0.0024, and the mean value is 0.0020 in the converter campaign.Flow field in bath shows a circulation from the center to the wallof converter. Vibration of bath appears when bottom blowing gas flow rate exceeds the critical value.