A physical modeling system was set up from the similarity theory for the bottom blowing argon process in a 120 t ladle of Tianjin Iron and Steel Group Co.， Ltd.Through the water model experiments， the influence of dif- ferent bottom blowing conditions on the complete mixing time in the ladle was measured， and the slag entrapment in ladle has been investigated.The influence of different operation parameters（time and flow rate of argon blowing） on non-metallic inclusions removal effect in ladle has been investigated， which provide the basis for improvements of o- riginal process.